Bulletin 116 

DEPARTMENT OF THE INTERIOR 

FRANKLIN K. LANE, Secretary 
BUREAU OF MINES 

VAN, H, MANNING. Director 


METHODS OF SAMPLING DELIVERED COAL 

AND SPECIFICATIONS FOR THE PURCHASE 
OF COAL FOR THE GOVERNMENT 



GEORGE S. POPE 












Bulletin 116 


DEPARTMENT OF THE INTERIOR 

FRANKLIN K. LANE. Secretary 

l/.S, BUREAU OF MINES 

VAN. H. MANNING. Director 


METHODS OF SAMPLING DELIVERED COAL 

AND SPECIFICATIONS FOR THE PURCHASE 
OF COAL FOR THE GOVERNMENT 



BY 


GEORGE S. POPE 




WASHINGTON 

GOVERNMENT PRINTING OFFICE 
1918 


\ 





V 


The Bureau of Mines, in carrying out one of the provisions of its organic act—to 
disseminate information concerning investigations made—prints a limited free edi¬ 
tion of each of its publications. 

When this edition is exhausted copies may be obtained at cost price only through 
the Superintendent of Documents, Government Printing Office, Washington, D. C. 

The Superintendent of Documents is not an official of the Bureau of Mines. His 
is an entirely separate office and he should be addressed: 


Superintendent op Documents, 

Government Printing Office, 

Washington, D. C. 


The general law under which publications are distributed prohibits the giving of . 
more than one copy of a publication to one person. The price of this publication is 
15 cents. 


First edition. May, 1916. 
Reprint. July, 1918. 


NOV 


o 


of 

19 fili 


2 




CONTENTS 



> _ 

^ I’age. 

Introduction.,.. 3 

Theory of sampling. 5 

The method of sampling as a part of coal specifications. 6 

Practical considerations. 6 

^loisture. 6 

Ash and heating value. 10 

Volatile matter. 10 

Sulphur and clinker. 11 

Need of experience and caution in sampling. 12 

Directions for sampling. 13 

Size of the gross sample. 13 

When to collect samples. 15 

Collection of gross samples. 16 

Wagonload sampling. 17 

Carload sampling. 17 

Cargo sampling. 18 

Sample receptacle.'. 20 

Collection of special moisture samples. 21 

Preparation of the gross sample. 23 

Sampling buckets. 29 

The mixing and reducing macliine. 30 

Collection of samples in the District of Columbia. 30 

The sampling room. 31 

Sealing and mailing. 35 

Reporting analyses. 39 

Coal specifications and proposals. 40 

Specifications and proposals for bituminous and anthracife coal. 46 

I. Proposals. 46 

II. Contractor’s bond. 46 

III. Reservations. 47 

IV. Quantity. 47 

V. Delivery. 48 

VI. Sampling. 48 

VII. Analyses. 48 

VIII. Bituminous and anthracite pea and buckwheat coal for power and 

heating plants. 48 

Description of coal desired. 48 

Award. 49 

Causes for rejection. 50 

Price and payment. 51 

IX. Antharcite coal—domestic sizes. 52 

Description of coal desired. 52 

Award. 52 

Causes for rejection. 53 

Price and payment. 53 

X. Information to be supplied by bidders. , 53 

Appendix A. 55 

Method of sampling coal deliveries. 55 

Publications on fuel technology. 59 

Index. 63 

s 




















































ILLUSTRATIONS. 


Page. 

Plate I. A, Crushed gross sample in conical pile; B, Crushed gross sample 

remixed in long pile; C, Reduced sample quartered. 2G 

II. A, Sampling bucket; B, Mixing and reducing machine. 28 

III. A, Coal-samphng plant; B, Double container. 32 

IV. A, Sampling riffle; B, Sealing container. 32 

V. Method of preparing a sample of coal by hand. 56 

Figuie 1, Design of a simple coal sampling plant. 31 

2. Working drawings for riffle for reducing coal sample. 33 


II 












METHODS OF SAMPLIKG DELIVERED COAL, AND TYPES OF 
SPECIFICATIONS FOR THE PURCHASE OF COAL FOR THE 
GOVERNMENT. 


By George S. Pope. 


INTRODUCTION. 

This bulletin is a revision of Bulletin 63 and is published by the 
Bureau of Mines in order that purchasers of coal for Government, 
State, municipal, or private use may be informed regarding advances 
or refinements in sampling coal deliveries and preparing specifications 
for the purchase of coal. 

The purchase of coal by the Government under specifications 
depending on the heating value of the coal, its content of ash and of 
moisture, and other considerations, rather than upon the reputation 
or trade name of the coal, was based on the fuel investigations begun 
by the Technologic Branch of the United States Geological Survey in 
1904. The plan was first adopted by the Treasury Department in 
1906. Since then the plan, variously modified in form, but the same 
in principle, has been gradually adopted by other departments until, 
at present, of the coal used by the Government, the total value of 
which approximates $8,000,000 annually, more than half is purchased 
under specifications. The Government publications deahng with the 
adoption by the Government of the specification plan, the number 
of contracts awarded on that basis, and the quality of the coal deliv¬ 
ered under such contracts in the several fiscal years covered by the 
reports are given in publications ® listed at the end of this bulletin. 

Under the authority of acts of Congress making appropriations for 
analyzing and testing fuels belonging to or for the use of the United 
States Government, a laboratory is maintained at the headquarters 
of the Bureau of Mines, 'Washington, D. C., where samples represent¬ 
ing deliveries of coal purchased under specifications for Government 
use are analyzed and tested. 

At this laboratory more than 1,200 samples have been analyzed 
and tested in one month. With the complete equipment and the 
efficient force employed, the analytical work has been so perfected 
that the analyses and heating-value tests of the samples received are 
as accurate as may be reasonably expected in laboratory work of this 
nature. 


1 See Bulls. 11, 41, aiul 119, Bureau of Mines. 


3 






4 


METHODS OF SAMPLING DELIVERED COAL. 


One of the serious drawbacks to the general adoption of the speci¬ 
fication method for the purchase of coal is the difficulty of obtaining 
at reasonable cost samples of coal that can be considered fairly repre¬ 
sentative of the commercial product delivered in wagons, railroad 
cars, or ships. Therefore the method of taking and preparing sam¬ 
ples for shipment to the laboratory has been given fully as much care 
as the making of the analyses and tests, and a general plan of collect¬ 
ing samples fairly representative of the delivered coal has been 
evolved through various modifications and improvements based on 
experience and increased knowledge of the physical and chemical 
characteristics of the various coals that are purchased by the Govern¬ 
ment. The method that , is in general use by the Government is 
described in the following pages. 

In connection with studies of the coal deposits of the country, of 
the best methods of preventing waste in mining, and of increasing 
efficiency in the utilization of coal belonging to or for the use of the 
Government, geologists and engineers of the United States Geolog¬ 
ical Survey and of the Bureau of Mines have visited more than 2,500 
coal mines scattered through all of the coal-producing States and 
Territories. From each mine 2 to 8 or more samples were taken, 
the number depending upon the size of the mine and its output. 
The analyses and descriptions of the samples collected up to the end 
of the fiscal year 1913 are published in Bulletins 22“ and 85,^ Bureau 
of Mines, and those of samples collected in the fiscal years 1914 and 
1915 are presented in Bulletin 123.® 

A study of the analyses of these samples and of the samples taken 
from cars shipped from a number of the same mines shows that the 
mine samples are as a rule of higher grade than the average commer¬ 
cial shipments, particularly with respect to containing a lower per¬ 
centage of ash and having a correspondingly higher heating value. 
This difference is due to the fact that the Government inspector, pro¬ 
ceeding on the basis of what can be done by a good miner, usually 
removes more of the partings of bone, slate, and other extraneous 
matter from his mine samples than the average miner does in ordi¬ 
nary practice, the aim of the miner being to get the maximum number 
of tons past the tipple inspection, as his earnings are based on his 
output. The average miner, therefore, does not always take as much 
care as he might in rejecting the impurities. The difference may be 
caused, too, by the presence of pieces of the mine roof and floor in 
commercial shipments. The Government inspector can readily 

a Lord, N. W., and others. Analyses of coals in the United States, with descriptions of mine and field 
samples collected between July 1, 1904, and June 30,1910: Bull. 22, Bureau of Mines, 1912, 1129 pp. In 
two parts. 

i> Fieldner, A. C., Smith, H. I., Fay, A. H., and Sanford, S., Analyses of mine and car samples of coal 
collected in che fiscal years 1911 to 1913: Bull. 85, Bureau of Mines, 1914,444 pp. 

c Fieldner, A. C., Smith, 11. I., Paul, J. W., and Sanford, S., Analyses of mine and car samples of coal 
collected in the fiscal years 1914 to 1916: Bull. 123, Bureau of Mines, 1918, 478 pp. 



THEORY OF SAMPLING. 


5 


exclude these from the mine sample, hut they often get into the 
commercial coal as a result of the character of the roof and floor 
and of the mining methods employed. The efficiency of the tipple 
inspection and the means employed in rejecting impurities when 
the coal is loaded into the railroad car are also factors that often 
largely account for the difference between mine and commercial 
samples. Most of the samples collected from the mines by the 
Government inspectors show a higher moisture content than com¬ 
mercial samples, because of the generally moist atmosphere of the 
mine and the precaution taken to prevent loss of moisture in the 
collection, preparation, and analysis of mine samples. 

When properly taken, the mine samples are of great value, as they 
indicate the general character of the coal and the uniformity of the 
coal bed and enable one to determine its probable value for any 
designated purpose, provided due consideration is given to the 
character of the partings, the roof, and the floor, and to the possi¬ 
bility of pieces from these being loaded with the commercial output. 

The collection of mine samples by the Bureau of Mines and the 
Geological Survey is done in a systematic manner, according to a 
prearranged plan, and the same procedure is always followed where 
circumstances permit. A special outfit for use in collecting mine 
samples has been developed. The method followed and a description, 
with illustrations, of the outfit are pubhshed in Bureau of Mines 
Technical Paper 1, entitled ^‘The Sampling of Coal in the Mine.” 

THEORY OF SAMPLING. 

To determine with utmost accuracy the ash content and heating 
value of a quantity of delivered coal would require the burning of the 
entire quantity, and special apparatus arranged to measure the total 
heat liberated, or would require crushing the whole quantity, and 
reducing it by an elaborate scheme of successive crushings, mixings, 
and fractional selections to portions weighing approximately 1 gram, 
the minute quantity which the chemist requires for each determina¬ 
tion. Either of these procedures is obviously impracticable if the 
coal is to be used for the production of heat and power. 

The method actually employed is to select portions from all parts 
of a consignment or delivery of coal and to systematically reduce the 
gross sample, obtained by mixing these portions, to quantities that 
the chemist requires for making ash determinations or that can be 
burned conveniently in the calorimeter, an apparatus for determining 
the heating value. The gross sample should be so large that the 
chance admixture of pieces of slate, bone coal, pyrite, or other 
impurities in an otherwise representative sample will affect but 
slightly the final results. Increasing the size of the gross sample 
tends toward accuracy, but the possible increase is limited by the 


6 METHODS OF SAMPLING DELIVERED COAL. 

cost of collection and reduction. In reducing the gross sample by 
successive crushings and halvings or fractional selections; the object 
is to procure a small laboratory sample that, upon analysis; will give 
approximately the same results as the gross sample itself; or, in fact, 
the entire quantity of coal from which the gross sample was obtained. 

THE METHOD OF SAMPLING AS A PART OF COAL SPECIFICATIONS. 

The method of sampling because of its importance as a definite 
commercial procedure, is clearly set forth in the specifications in use 
by the Government, and is made a. part of the contract. In order 
that there may be uniformity and similarity in specifications used by 
the different branches of the Federal service for the purchase of coal, 
the Bureau of Mines has prepared specifications for general use by 
the Government. These specifications in their present form are the 
result of development following years of experience and satisfactory 
use by various Government branches. The specifications printed on 
pages 46 to 58, are typical of the Federal specifications in use for the 
fiscal year 1915-16. It is recognized that in general specifications, 
such as presented, certain requirements have to be of wide applica¬ 
tion, in order to cover a variety of conditions, not only as to char¬ 
acter and quality of coal, but as to type of furnace equipment, size 
of deliveries, and method of delivering. 

PRACTICAL CONSIDERATIONS 

MOISTURE. 

The specifications that were used for the purchase of coal on the 
heat-unit basis prior to the fiscal year 1912-13 were on the B. t. u. 
(British thermal unit) ^'as received’’ basis; that is, payment for 
delivered coal was directly affected by the moisture content of the 
sample received by the laboratory. This method was based on the 
assumption that the moisture in the samples collected at the time of 
weighing and delivery could be preserved with slight loss during the 
storing and subsequent working down of the gross sample to a quan¬ 
tity convenient for transmittal to the laboratory and in its later treat¬ 
ment in the laboratory. From experiments that have been made and 
from a large mass of data, it is known that the moisture content of 
coal does not remain constant, and that the moisture content reported 
by the laboratory may be as much as 5 to 10 per cent lower than that 
actually contained in excessively wet or high-moisture coal at the 
time of weighing. 

In one investigation, 254 gross samples were reduced, at the deliv¬ 
ery point, to samples weighing approximately 5 pounds each and 
then the 5-pound samples were divided into two equal parts (^dupli¬ 
cates”), which were placed in mailing cans and sent to the Bureau of 
Mines for analysis. The moisture contents of the ^duplicates” were 


PRACTICAL CONSIDERATIONS. 


7 


presumably identical, but analysis showed that the average difference 
between the moisture contents of the 254 pairs of ^^duplicates'’ was 
9.256 per cent and the maximum difference was 3.6 per cent. These 
figures indicate the moisture differences that may exist even after the 
gross sample has been reduced to approximately 5 pounds, but they 
do not show the moisture, lost by the gross sample while in storage 
and while being reduced to 5 pounds. As stated above, the total loss 
of moisture may be as much as 5 to 10 per cent in high-moisture or 
excessively wet coals.. 

As a sample loses moisture, its B. t. u. ^‘as received" value cor¬ 
respondingly rises, with the result that the price for delivered coal 
determined on the ^^as received" value is, with rare exceptions, 
higher than that warranted by the quality of the coal at the time of 
weighing. As a general statement, payment based on the ^^as 
received" B. t. u. value will be higher than warranted, unless the 
sampling and laboratory work can be carried on under conditions 
that minimize moisture loss, as under freezing temperatures. 

Kecognizing the uncertainty involved in taking the moisture deter¬ 
mination in the laboratory as representative of the moisture content 
of the delivered coal and the consequent possibility of payment of a 
higher price than is warranted, the Bureau of Mines recommends that 
the heating value in coal specifications be on the ^‘dry-coal" basis. 

The fact is recognized that the amount of moisture contained in 
coal produced from day to day from the same mine, or group of mines 
working the same bed, is largely accidental, and is a matter over which 
the buyer and seller have only slight control. However, in order to 
place a negative value on high-moisture coals and to protect the Gov¬ 
ernment against the delivery of coals containing excessive amounts 
of moisture, the specifications require the bidders to specify the maxi¬ 
mum moisture content in coal offered. This value becomes the 
standard of the contract. 

If coal of uniform B. t. u. dry-coal" value is delivered on a con¬ 
tract, the contractor receives the advantage on any dehvery in 
which the . moisture content approaches the maximum specified, 
because he is paid for the weight of water contained in the coal in 
excess of a normal amount, whereas if the coal is very dry, containing 
less than the normal amount of moisture, the purchaser receives the 
advantage. 

For example, coal is deUvered under a contract in which the 
standards are 14,300 B. t. u. per pound ‘'dry coal," and a maximum 
moisture content of 3.5 per cent. The heating value of a ton (2,240 
pounds) of “dry coal" would be 32,032,000 B. t. u. Assume that 
the average moisture content of deliveries for a year is 2.5 per cent, 
then for every 2,240 pounds of “dry coal" having a heating value 
of 32,032,000 B. t. u., the purchaser is required to pay for 56 pounds 
67590°—Bull. 116—18-2 


8 METHODS OF SAMPLING DELIVERED COAL. 

of water at the same rate per ton as for ‘‘dry coal,” but as this per¬ 
centage of moisture in average deliveries is inherently a constituent 
of the coal, it is considered as part and parcel of the coal by both the 
purchaser and the seller. If the coal delivered contains 3.5 per cent 
moisture, to procure 32,032,000 B. t. u. “dry coal,” the purchaser 
has to pay 1 per cent more for coal because of the excess water 
above the normal amount, whereas if the coal contains 1.5 per cent 
moisture, the purchaser pays 1 per cent less. As the variations in 
moisture content, 1.5 or 3.5 per cent, are largely accidental, the 
season of the year being partly responsible for them, it is equitable 
that the purchaser and seller should share the uncertainty. The 
purchaser justly has a right, however, to demand that the seller shall 
guarantee a maximum moisture content, as a means of enabling the 
purchaser to compare one coal with another, as a guaranty that the 
seller will observe precautions against dehvering coal that is unduly 
wet, and as a basis for adjusting the price of exceptionally wet coal. 

The United States Weather Bureau in its annual reports gives the 
total precipitations per month and the maximum in 24 hours for 
different sections of the United States. At Washington, D. C., the 
greatest rainfall recorded for one month is 5.89 inches, and for 24 
consecutive hours is 3.67 inches. 

As an example of the effect of a heavy rain on a car of coal in 
transit, a precipitation of 3 inches of water on a loaded 50-ton car, 
area of top about 360 square feet, would increase the weight of the 
coal 5.01 per cent, provided none of the water drained out or evap¬ 
orated. It is obvious that if this coal is weighed and delivered imme¬ 
diately, special samples for moisture determinations should be col¬ 
lected and prepared at once and sent to the laboratory, as a basis for 
equitable adjustment of payment on accoimt of the excessive amount 
of water in the coal. As the weight of the coal was increased by the 
excess water, there should be a corresponding decrease in the price 
to be paid. 

If a railroad car or a wagon so rained on was not imloaded im¬ 
mediately after weighing and the special moisture samples were not 
properly collected, prepared, and sent hermetically sealed to the 
laboratory, it is obvious that the purchaser would pay a higher price 
than warranted, especially if the car or wagon stood for some time 
before sampling and some of the water drained out. Further, if the 
coal was not immediately unloaded and sampled or if the car 
continued in transit after weighing, then the coal at the top would 
soon dry; and in either case the effect of the 3-inch rainfall, as indi¬ 
cated by the analysis, might be only a fractional percentage of the 
moisture contained in the coal at the time of weighing. 

The determination of the moisture in coal dehvered from stock 
piles is often of great importance, for the proportion of moisture 


PRACTICAL CONSIDERATIONS. 


9 


contained in the small sizes, which are most abundant near the center 
of a stock pile and which absorb the rains, and melting snows in 
districts of heavy snows, may be from 10 to 15 per cent higher than 
when stocked. It is apparent, therefore, that special moisture sample 
determinations are necessary for equitable adjustment of payment 
on account of excessive moisture in coal which is stocked in piles 
exposed to the weather. 

The specifications provide for the collection of ‘‘special moisture 
samples’^ if, in the opinion of the Government officials sampUng it, 
the delivery contains moisture in excess of that guaranteed by the 
contractor. The “special moisture samples’’ are prepared in a man¬ 
ner to minimize moisture losses and may be taken and prepared inde¬ 
pendently of the gross samples collected for the determinations of 
heating value (B. t. u.), ash, and other specified data. If the analysis 
of the special sample shows a moisture content in excess of the con¬ 
tractor’s guaranty, a proportionate deduction is ma^de from the 
price to be paid for the coal. 

“Special moisture samples” representing coal as dehvered should 
be preserved in such a way as to minimize moisture loss, because if 
the moisture content of the sample, as shown by analysis, is less than 
the actual moisture content of the coal at the time it is weighed, 
either because of the sample being nonrepresentative or because of 
subsequent moisture loss during the storage or the preparation of the 
sample, the price to be paid for the coal delivered is correspondingly 
increased and an injustice is done the purchaser. It is equally 
important to protect the sample during coUeetion or storage from 
becoming wet by rain, snow, or water from any other source, in order 
to insure that the sample represents the delivered coal. Evidently, 
therefore, particular attention should be given to procuring for the 
laboratory a sample containing the same percentage of moisture as 
the delivered coal. 

To minimize moisture loss, the sample must be placed in a tight 
container and stored in a cool place before it is reduced. Moreover 
the sample should be reduced and transmitted to the laboratory as 
soon as practicable. It is well to remember that a sample taken 
from coal that has been exposed to a relatively high temperature, 
as coal from a boiler or furnace room, or from adjacent bins, has lost 
moisture and does not represent the coal as delivered. For the 
same reason the samples should not be stored in a boiler room. 

If the contractor does not guarantee a moisure content lower than 
can be actually maintained on an average, the collection of “special 
moisture samples” and the making of price corrections on account of 
excessive moisture will seldom be necessary. Thus, the placing of 
heating value (B. t. u.) on the “dry coal” basis, with a maximum 
moisture content, eliminates frequent corrections of price on account 
of uncertain moisture variations. 


10 METHODS OF SAMPLIITG DELIVERED COAL. 

ASH AND HEATING VALUE. 

The heating value of coal from the same mine or from a group of 
mines operating the same bed of uniform character is directly influ¬ 
enced by the percentage of ash. By ash is meant earthy matter and 
impurities that do not burn. As the proportion of ash inherent 
(sometimes termed ^intrinsic ash’’) in the coal substance as a rule 
does not vary widely in coal from the same bed, the heating value is 
largely determined by the amount and character of the free (some¬ 
times termed ^‘extraneous”) impurities, and hence the manner in 
which coal is cleaned and prepared at the mine may greatly affect 
the heating value of commercial shipments. In collecting samples, 
therefore, it is of utmost importance that the samples should con¬ 
tain within reasonable limits the same proportion of impurities as 
the delivered coal from which they were taken. 

As the specifications provide for adjustment of price according 
to the ash content or the heating value, or both, it is evident that 
samples taken from delivered coal should show, by analysis, practi¬ 
cally the same ash content and heating value as the delivered coal. 
In other words, the sample should contain the same proportion of 
slate, bony coal, pyrite and other impurities as the quantity deliv¬ 
ered, in order that the price adjustment based on the analysis may 
be fair to both purchaser and seller. Obviously, it is important to 
guard against any accidental admixture of sand, cement, clinkers, 
or other foreign matter while the sample is in storage or while it is 
being prepared for transmittal. 

In this connection, attention is called to the fact that the gross 
sample should contain the same proportion of lump and fine coal as 
the delivered coal, for it has been determined that fine or slack coal 
may have an ash content, or a heating value, different from lump 
coal from the same shipment. 

VOLATILE MATTER. 

The volatile matter® of coal, as shown in analyses, generally con¬ 
tains some inert noncombustible matter, the proportion of which 
may range from 1 to 15 per cent. The character of the volatile 
matter in any given coal and the temperatures at which it is given off 
bear directly on the design and operation of furnaces for burning 
the coal efficiently and without smoke. The proportion of combus¬ 
tible and noncombustible constituents in the volatile matter and the 
character of the combustible constituents differ in different coals, 
and, therefore, the heating value of a coal can not be determined 
from a proximate analysis. Moreover, different coals with the same 
proportion of volatile matter may not behave alike in the furnace. 


o Porter, H. C., and Ovitz, F. K., The volatile matter of coal: Bull. 1, Bureau of Mines, 1910,56 pp. 



PEACTTCAL CONSIDEEATIONS. 


11 


In order to determine the comparative value of two coals for the same 
purpose, it is important to know both their chemical composition 
and their heating value. Hence the specifications recommended 
by the Bureau of Mines provide that before final awards of con¬ 
tracts, practical service tests may be made to determine the relative 
suitability of the coals offered. 

In the specifications the contractor is required, in addition to 
giving the name and the location of the mine or mines producing 
the coal and the name of the coal bed worked, to specify the volatile 
matter content and other proximate analysis determinations of the 
coal he proposes to furnish. The volatile matter content he specifies 
becomes the standard of his contract, and delivery of coal with a 
different percentage of volatile matter, indicating the substitution of 
a coal other than that offered, may result in the coal being rejected 
and the Government purchasing coal in the open market (the con¬ 
tractor being charged with the difference, if any, in cost) or in the 
contract being canceled. 

The Government does not consider any scheme of applying penal¬ 
ties on account of variations in volatile matter equitable, because the 
character of the volatile matter and its heating value are not neces¬ 
sarily indicated by the volatile matter determination, and because 
this determination is made by an empirical method whereby dupli¬ 
cate determinations on the same sample may differ as much as 2 
per cent in different laboratories, or, in fact, in the same laboratory. 
Accordingly, no corrections in price are made for variations in 
volatile matter. 

The bureau has received copies of commercial and municipal speci¬ 
fications drawn up apparently without regard to these facts. One 
specification, for instance, provides for a correction of 2 per cent in 
price for each 1 per cent of volatile matter in excess of the standard 
guaranteed. On a coal sold at $3 per ton a deduction of 12 cents per 
ton might be made for an apparent excess of 2 per cent in volatile 
matter, when, in fact, the actual volatile matter of the coal was not 
above the standard. Specifications of this nature furnish legitimate 
grounds for opposition from coal companies and do much to discredit 
the specification method for the purchase of coal. 

SULPHUR AND CLINKER. 

Sulphur is commonly present in coal in combination with iron or 
other elements. For a long time it was thought that the sulphur 
formed clinker, but recent investigations point to the fact that sulphur 
is not the only cause of clinkering; in fact, there may be no difficulty 
from clinker in burning coal containing as much as 5 per cent or more 
sulphur. The relative proportions of iron, sulphur, lime, alumina, 
silica, etc., in the ash affect its fusibility, whereas the method of 


12 METHODS OF SAMPLING DELIVERED COAL. 

firing and the rate of combustion are important factors in the forma¬ 
tion of clinkers. The exact relation of clinkering to the constituents 
of the ash is not known so well that one can definitely predict from 
an analysis of the ash whether a coal will or will not clinker. At 
many power plants the fireman slices the fire too often and works 
the ash up from the grates into the hot coal bed, where it melts and 
fuses into heavy, dense masses of clinker. At high rates of combus¬ 
tion the ash in a given coal may clinker (though at lower rates it 
does not) because of the ash being raised to the fusing tempera¬ 
ture. The fact that the percentage of sulphur does not necessarily 
indicate the behavior of the coal in the furnace is recognized in the 
specifications recommended by the Bureau of Mines. The contrac¬ 
tors, however, are required to specify the sulphur content so that 
standards for the coals to be delivered may be established. 

Many commercial and municipal specifications exact penalties for 
a slight increase in the sulphur content, although coal of high sulphur 
content may chnker less and its heating value may be higher. One 
specification received by the Bureau of Mines exacts a deduction of 
5 per cent in price for each 1 per cent of sulphur in excess of the 
standard. In the case of a coal supplied at $3 a ton, the presence of 
1 per cent of sulphur in excess of the standard, as indicated by 
analysis, would often result in an unwarranted deduction of 15 cents 
a ton. Under such a contract, the variations which it is recognized 
exist in sampling and analysis may cause a contractor unjustly to 
suffer a heavy deduction. 

Both the sulphur and the volatile-matter content should be used 
to classify coals and to identify the coal guaranteed. Variations 
indicating the substitution of an unsatisfactory coal should be con¬ 
sidered cause for rejection of the coal or for cancellation of the 
contract. 

NEED OF EXPERIENCE AND CAUTION IN SAMPLING. 

Persons without experience generally select a sample better than 
the average run of the coal delivered. Occasionally, a lump unusually 
free from layers of slate and impurities, and representing the best coal 
in the lot rather than the average, is selected. After being broken it 
is shipped to the laboratory in a cloth sack, so that it loses moisture 
during transit. The analysis of such a sample necessarily indicates a 
value higher than that of the coal delivered. As a quantity of coal 
may vary greatly in composition, containing not only what may be 
termed coal proper with certain more or less constant impurities, but 
also slate, pyrite, and bony coal, a lump may be anything from 
almost pure coal to material without fuel value. Hence the analysis 
and test of a single lump may indicate a composition greatly different 
from that of the coal at hand. It is well to remember that, as the 


DIKECTION-S FOR SAMPLING. 


13 


larger lumps of coal roll down and collect near the bottom of a pile or 
load, a sample taken entirely from near the floor does not always 
fairly represent the whole. 

In spite of every precaution taken to prevent loss of moisture dur¬ 
ing the collection, preparation, and analysis of samples, it is certain 
that loss of moisture may occur; also there may be too little or too 
much slate, bony coal, or other foreign matter collected in what is 
otherwise a truly representative gross sample, so that the determina¬ 
tion of the heating value or ash content does not strictly agree with 
the actual value of these factors in the coal dehvered. However, an 
experienced collector, by using good judgment and following the gen¬ 
eral directions given for collecting and preparing samples, can obtain 
samples so fairly representative that the results of the analyses are 
reasonably accurate. The suggestions that foUow are presented for 
the guidance of those who wish to send representative samples to a 
laboratory for analysis and heating-value tests. 

DIRECTIONS FOR SAMPLING. 

SIZE OF THE GROSS SAMPLE. 

The number of pounds to be taken as a gross sample to represent 
a given lot of coal varies with the character and condition of the coal, 
and not with the amount of coal to be sampled. The character and 
proportion of the bony coal, slate, etc., and the size of the particles 
of both coal and impurities are the governing factors. It is there¬ 
fore evident that samphng should not be left to an inexperienced 
person, but should be done by one who is thoroughly familiar with 
the signiflcance of these factors and has some knowledge of the coal 
to be sampled. 

There is greater probability of taking too little than of taking too 
much coal for a gross sample. It is generally true that the larger the 
gross sample the less is the chance of its being nonrepresentative. 
Large samples must be taken in sampling coals that carry a varying 
proportion of large pieces of slate, bony coal, or pyrite, for it is 
evident that including or excluding large pieces of the impurities 
must affect the analysis of a small sample considerably; hence, the 
analysis may not indicate the quality of the coal sampled and, conse¬ 
quently, may be worthless for determining the price to be paid for 
the coal. If the free impurities are small particles and are well dis¬ 
tributed throughout the coal, representative samples may be obtained 
easily. 

Bailey® has contributed valuable information to the study of sam¬ 
pling coal. He gives the results of experiments and studies made to 
determine the size of samples and methods of sampling required 

a BaUey, E. G., Accuracy in sampling coal. Paper read before industrial division of American Chemical 
Society, Baltimore, Dec. 31,1908. How to sample coal and coke. Fuel Testing Co., Bull. 4,1910. 




14 


METHODS OF SAMPLING DELIVERED COAL. 


for reliable analyses. The ^‘size-weight’’ ratio or percentage, that 
is, the ratio of the percentage of the largest pieces of slate to the 
total weight of the sample, is shown, and appears to be the most im¬ 
portant factor for consideration in the sampling of coal. The fun¬ 
damental principles as stated by Bailey were recognized in the experi¬ 
ments and investigations conducted by the Bureau of Mines. The 
conclusions reached by the bureau as to the size of samples to be col¬ 
lected, and the sizes to which a sample should be crushed at its 
various stages of reduction in quantity, substantiate the results of 
Bailey’s work. 

As a result of these experiments and tests it has been found that 
as the size of the sample is decreased the differences between separate 
samplings become greater and greater. In the case of very small 
samples ® the difference may become equivalent to that between pure 
coal and slate. On the other hand, it has been found that as the 
weight of the sample is increased, the difference rapidly decreases, 
imtil a point is reached where the accuracy obtained by taking larger 
samples is affected but slightly. This would not ordinarily be war¬ 
ranted, because of the expense which would be involved in making 
special provisions for handling the very large samples. 

The large differences obtained with small samples show very forc¬ 
ibly the necessity for collecting large gross samples in order to insure 
the results of analyses and reliable heating-value tests, from which 
the proper price to be paid for delivered coal can be determined and 
injustice to either seller or buyer prevented. 

As a result of the tests it has been established that a gross sample 
of approximately 1,000 pounds is sufficient to give reliable results 
for coals comparatively easy to sample; that is, coals relatively free 
from the “extraneous” impurities. It may be necessary to collect 
larger gross samples, even 1,500 pounds or more, for coals containing 
a considerable proportion of impurities in large pieces, or large lumps 
of coal with streaks of bone, slate, or pyrite, or sulphur balls and 
lenses. 

Whether a delivery consists of 1 ton, 500 tons, or more, the need 
of the gross sample weighing 1,000 pounds or more is the same. One 
such sample carefully taken and reduced to a quantity convenient 
for transmittal to the laboratory can well represent a delivery of 
several himdred tons, a thousand tons, or more. 

For convenience, however, and to avoid long storage of the sam¬ 
ples, the Bureau of Mines considers it advisable that one sample of 
1,000 pounds, or more, should be collected weekly in the case of 
Government contracts calling for more or less regular deliveries each 
week. If, however, the quantity delivered during a week is rela¬ 
tively small, then the sample may represent the coal delivered during 


a In this bulletin the word slate is used as a commercial, not a geological, term and signifies shale. 



DIRECTIONS FOR SAMPLING. 


15 


a longer period. To facilitate accounting, many branches of the 
Government service order contractors to deliver in certain quantities, 
usually 100 to 500 tons. In such cases the samples are collected to 
represent the order without special regard to the period covered, 
and one or more gross samples of 1,000 pounds or more each are 
collected, as may be most practical and expedient in view of the 
facilities for sampling and the other considerations involved. 

In sampling cargo deliveries of 5,000 and more tons, the Bureau 
of Mines collects from 3,000 to 4,000 pounds of coal as a gross sample. 
In order that the preparation of the samples may proceed while the 
cargo is being loaded, after approximately 500 pounds has been 
collected it is reduced to a quantity convenient for mailing to the 
laboratory, and each succeeding 500 pounds is likewise reduced. 
This procedure makes unnecessary the accumulation of a quantity 
of coal that can not be systematically and conveniently handled in 
the short time and the small space usually available. Two or more 
of the samples are combined and reduced to one in the laboratory, 
and four or five analyses are usually made for a cargo, and a report 
on the cargo is obtained by averaging the analyses. The samples 
may, however, be mixed in the laboratory and only one analysis 
made to represent the cargo. Though the experiments which have 
been made indicate that a sample of approximately 1,000 pounds 
will give results fairly representative of the cargo, the objection to 
the 1,000-pound sample is that it is too small to allow of the frequent 
collection of shovelfuls or portions of any quantity throughout the 
loading of a large cargo. As it generally happens that coal from a 
number of mines is loaded into the same cargo, it is desirable to 
collect a considerable quantity of coal, so that each mine may be 
well represented in the gross sample. It is obvious that the more 
frequently the portions are collected and the greater the quantity 
sampled, the less the probability that the sample will be nonrep¬ 
resentative; accordingly, the bureau considers that in sampling 
5,000-ton cargoes safety lies rather in the larger gross sample. 

WHEN TO COLLECT SAMPLES. 

The best opportunities for procuring representative samples are 
afforded while the coal is being loaded into or unloaded from railroad 
cars, ships, and barges, or while it is being dumped from wagons. 
Once the coal is stored in piles or bins, or loaded on cars or vessels, 
the procuring of representative samples is practically impossible 
unless the whole quantity of coal is immediately handled again and 
the conditions for sampling become favorable. Samples collected 
from the coal exposed in piles, bins, barges, cars, or ships can be 
considered representative only under the condition that the mass 
of coal is homogeneous throughout. Such a condition is highly 
67590°—Bull, 116—18-3 


16 


METHODS OF SAMPLING DELIVERED COAL. 


improbable and uncertain, and the analysis of samples collected 
from the surface may give results that are very unreliable as indi¬ 
cating the nature of the entire quantity, and that may be worthless 
as a basis for determining an equitable price to be paid for the coal. 

COLLECTION OF GROSS SAMPLES. 

When coal is being loaded into or unloaded from wagons, railroad 
cars, ships, or barges, a shovel or a specially designed tool may be 
used for taking portions or increments of 10 to 30 pounds to make 
up the gross sample of coal. As the size of the increments should 
be governed by the size and weight of the largest pieces of coal and 
impurities, increments of more than 30 pounds may be required for 
coals containing large pieces of coal and impurities. 

If one chute or conveyor is used for delivering a considerable quan¬ 
tity of coal to or from wagons, cars, or ships, it may prove expeditious 
and economical to devise a mechanical means for collecting portions 
from fractional parts of the discharged coal, or continuously deflect¬ 
ing a portion of the coal as it falls down the chute, or diverting from 
the conveyor deflnite portions of coal, and thus mechanically and 
automatically collecting the gross sample. 

The mechanical collection of samples is preferred to shovel sam¬ 
pling, as it eliminates the personal equation. The mechanical sam¬ 
pler does not discriminate for or against taking more or less slate 
or other impurities. A person should collect samples with a shovel 
in the main without regard to impurities, leaving the amount of the 
impurities included in a sample largely to chance, as it is impossible 
to rate correctly the proportion of the impurities concealed in the 
coal, however competent the sampler may be. A mechanical sam¬ 
pler should preferably take the whole of the stream of coal flowing 
down the chute a part of the time rather than a part of the stream 
aU the time, because the sizes and character of the pieces of coal and 
impurities are not apt to be evenly distributed across the stream. 
Excellent opportunity is afforded for procuring representative 
samples if the entire consignment of coal is crushed immediately 
after it is weighed and delivered, for then the samples can be col¬ 
lected from the crushed coal. If the coal is conveyed from the 
crusher by a conveyor, means can be devised for mechanically and 
automatically diverting from the conveyor definite portions of 
coal to make up the gross sample. 

The portions should be regularly and systematically collected, so 
that the entire quantity sampled will be represented proportionately 
in the gross sample. The interval at which the portions are collected 
should be regulated so that the gross sample collected wiU weigh not 
less than approximately 1,000 pounds. If the coal contains an 


DIRECTIONS FOR SAMPLING. 


17 


unusual proportion of impurities, such as slate, bony coal, and 
pyrite, and if the pieces of such impurities are very large, it will be 
necessary to collect gross samples of even 1,500 pounds, or more, but 
for slack coal and for small sizes of anthracite, if the impurities are 
not in abnormal proportion or in pieces larger than about three- 
quarters of an inch, and are evenly distributed throughout the 
coal, a gross sample of approximately 600 pounds may prove suffi¬ 
cient. The gross sample should contain the same proportion of lump 
coal, fine coal, and impurities as the coal delivered. As soon as the 
portions are collected they should be deposited in a receptacle 
having a tight-fitting lid provided with a lock. 

WAGONLOAD SAMPLING. 

A gross sample taken by hand from coal delivered by wagon at a 
Government building should consist of shovelfuls of coal taken from 
the first, second, or third wagonload as it is being discharged, the 
number of shovelfuls taken and the loads sampled being dependent 
on the number of loads which the gross sample is to represent. If 
the coal is discharged immediately into a crusher, it is preferable to 
collect shovelfuls of the crushed coal. 

If it is desired to sample coal delivered in small lots by wagons to a 
large number of buildings from one source of supply where the coal 
is aU weighed, and if the Collection of samples at each building wiU 
involve considerable expense, samples may be conveniently collected 
at minimum expense at the source of supply when the coal is loaded 
into the wagons. In such case the samples are collected without 
regard to delivery points, the object being to sample the coal loaded 
into the wagons. At the end of the month or upon the completion 
of an order the corrected price per ton, if there be any corrections on 
account of coal varying from the standards guaranteed by the con¬ 
tractor, applies to each individual delivery point. Shovelfuls of coal 
should be taken from each wagonload, or every second or third, etc., 
wagonload, the number of shovelfuls taken and the number of wagon¬ 
loads sampled being dependent upon the number of loads which the 
gross sample is to represent. 

It is important to obtain representative portions of coal from every 
part of the delivery, so that the sample will show the quality of the 
delivery or order as a whole. The gross sample should contain about 
the same proportion of lump coal, fine coal, and foreign matter as the 
coal delivered. 

CARLOAD SAMPLING. 

Samples taken from railroad cars should not be limited to a few 
shovelfuls of coal procured from the top of a car, for the size of the 
coal and the proportion of foreign matter may vary from the top to 


18 


METHODS OF SAMPLING- DELIVERED COAL. 


the bottom of the car. The only way to obtain a representative 
sample is to take a number of shovelfuls or portions of coal from 
different points in a car, from top to bottom and from end to end, 
while the coal is being loaded or unloaded. 

When a shipment of coal is sampled at the mine, shoveKuls or 
portions of coal should be taken systematically as the coal is loaded 
into the railroad car, and with such regularity that the sample will 
represent the entire carload. The frequency of collecting the por¬ 
tions will depend on the number of cars of coal to be represented by 
one gross sample. If only one carload is to be sampled, a gross 
sample of 1,000 pounds, or more, should be collected. If two or 
more cars of coal are to be represented by the sample, proportionate 
amounts to make up the gross sample should be taken from the coal 
as it is loaded into each car. The samples should be taken after the 
coal has been prepared for market; that is, if the coal is passed over 
picking tables or pickers are employed on the car to remove the 
impurities from the coal, the samples should be taken only after the 
coal has had its final preparation. 

When sampling coal delivered from open cars and unloaded by 
hand shovelfuls should be taken at regular intervals as the coal is 
unloaded into wagons or bins. 

When coal is being sampled from dump cars, ladlefuls (see p. 19) 
or shovelfuls should be taken from the stream of coal being discharged 
to the bins or ship. If the discharged coal is immediately crushed 
the gross sample should preferably be collected after the coal leaves 
the crusher. 

If a number of carloads are delivered on an order or during a short 
period the preparation of a gross sample of 1,000 pounds or more for 
each car would involve considerable time, labor, and expense at the 
delivery point, as well as in the laboratory; in fact, a gross sample for 
each car would not be required, for if a gross sample is carefully taken 
and prepared it can well represent a number of cars. If a gross sample 
is collected to represent two or more cars representative portions of 
the coal should be taken in equal quantities from each car. 

The method followed by the Bureau of Mines in sampling coal 
discharged from railroad cars directly into ships is given under 
“Cargo sampling.” 

CARGO SAMPLING. 

In sampling cargoes, as in sampling carloads, portions of coal 
should be taken in equal quantities and at frequent and regular 
intervals so as to represent proportionate parts of the consignment 
as a whole, either while the coal is being loaded or unloaded. There 
is no assurance that a sample or a series of samples taken from the 
top of the cargo represents the cargo as a whole; in fact, it is very 
doubtful if such samples are ever representative 


DIRECTIONS FOR SAMPLING. 


19 


The Bureau of Mines has charge of the sampling of cargo ship¬ 
ments of coal to the Isthmus of Panama for the Panama Rail Road 
Co. The coal, which is loaded from piers at Hampton Roads, Nor¬ 
folk, and Newport News, Va., is dumped directly from railroad cars 
into ships carrying from 4,000 to 12,000 tons of coal. The method 
followed is to collect portions of coal from every railroad car dumped. 
From 30 to 60 pounds are taken from each car sampled, the quantity 
taken depending on. the size of the cargo. From 3,000 to 4,000 
pounds are usually collected as a gross sample to represent a cargo 
(see p. 15 under ‘‘Size of the gross sample”)- The gross samples 
are reduced in successive stages as collected, rather than accumulated 
and later reduced to quantities convenient for transmittal to the 
laboratory. 

The portions making up the gross samples are taken from the coal 
as it. is discharged from the bottom-dump cars by the use of a shovel 
or a specially constructed ladle. The ladle has a handle about 5 feet 
long and a bowl 1 foot in diameter at the top, 9 inches at the bottom, 
with depth of 9^ inches, and holds from 25 to 30 pounds of coal. To 
collect samples with the ladle, it is rested on the rails of the track or 
on the chains that support the gates of the car. Two ladlefuls are 
usually taken from a car, one from one side and the other from the 
other side at the opposite end, thereby obtaining portions from dif¬ 
ferent parts of the car. Care is observed to not collect portions of 
the first or last coal spilling from the car, for the moisture content or 
proportions of foreign matter in such coal may render the sample 
unrepresentative. If circumstances permit, the ladle is shifted and 
filled from different sections of the stream of falling coal. It some¬ 
times happens that the coal is discharged very rapidly, in which case 
the collector must be alert to collect portions at the most desirable 
periods and must take care that the coal does not wrench the ladle 
out of his hands or jerk him down and do him bodily injury. 

The method of sampling cargo shipments has been established as 
the result of numerous experiments, and it has been determined that 
the analytical reports obtained are representative within limits 
reasonably to be expected for work of this nature. 

The bureau is making a study of the conditions on the piers, with 
a view of devising means whereby the samples can be automatically 
and mechanically collected, prepared, and reduced to quantities 
convenient for transmittal to the laboratory. At one of the three 
railroad terminals loading at Hampton Roads, Va., the bureau has 
installed a crusher for crushing the gross samples to ^-inch mesh 
and finer, and parting devices for reducing the samples in quantity, 
thereby eliminating the hand preparation of samples. It is 
proposed to install crushers and equipment at the other two points. 


20 


METHODS OF SAMPLING DELIVERED COAL. 


Because of the suddenness with which the coal may break through 
and drop out of the railroad car after the gates are open and because 
of the momentum of the rapidly falling coal, it may be impossible to 
collect a satisfactory sample by attempting to catch coal in a shovel 
or ladle. In such event, it may be necessary to collect shovelfuls of 
the coal that has overflowed on the pier. If beams 10 to 12 inches 
wide span the pockets immediately underneath the car, a fairly 
satisfactory sample can often be collected in shovelfuls from the coal 
lodging on the beams. 

Though the collector may use the shovel or ladle to the best of his 
ability, these tools may collect portions of coal that do not contain 
lump coal in the same proportion that exists in the car. Especially 
may this occur if the coal contains a large proportion of lumps of 
considerable size. In that event, the collector should collect portions 
of lumps from time to time and add them to the sample. Necessarily 
the collector must be relied upon to collect a sample under these 
conditions that will fairly represent the proportions of lump and 
slack coal contained in the coal sampled, and it follows that the 
collector must have experience in sampling and be able to judge the 
coal and the sample. 

In sampling large quantities of coal in a short period, the collector 
frequently works under disadvantages and has not the opportunity 
to select more leisurely and methodically portions of coal to make 
up a gross sample, as he can in sampling wagonload deliveries or in 
single carloads or barges unloaded by shovel, clam shells, or grab 
buckets, and this fact should be considered in comparing the results 
of sampling cargo with wagon or railroad-car deliveries. 

In collecting samples from coal as it is unloaded from a ship, the 
same general instructions apply; the cargo being systematically 
sampled during the entire period of unloading, so that samples wiU 
be collected which represent the quantity as a whole. If unloaded 
by grab buckets or into barrows, shovelfuls should be collected at 
regular intervals from the buckets or barrows. If the coal is crushed 
immediately after it is unloaded, it is preferable to collect samples 
from the crushed coal. 

SAMPLE RECEPTACLE. 

As the wagons or railroad cars may arrive irregularly at the build¬ 
ing or plant and the coal be intermittently unloaded, a metal recepta¬ 
cle or wooden box of a size to hold a gross sample of at least 1,000 
pounds, with a tight-fitting lid which can be locked, is required for 
holding the portions of coal taken from each wagon or car until the 
gross sample is completed. In sampling cargo deliveries, buckets 
holding 60 to 70 pounds may prove more satisfactory to use for 
receiving the portions making up a gross sample, as the samples are 


DIRECTIONS FOR SAMPLING. 


21 


usually worked down as the loading progresses and the buckets are 
convenient for carrying the coal to the space available for preparing 
the gross samples. If the gross samples are stored, a box should be 
provided or else a sufficient number of buckets with tight-fitting lids 
and locks should be available in order to preserve the integrity of the 
sample. 

The buckets, boxes, or receptacles should be inspected each time 
before using and thoroughly cleaned to remove the coal dust remain¬ 
ing from previous samples and any foreign matter that may by 
chance be in them. 

COLLECTION OF SPECIAL MOISTURE SAMPLES. 

During the collection of gross samples and their reduction to quan¬ 
tities that are convenient for transmittal to the laboratory and that 
correctly represent the ash, sulphur, and heating value of the coal 
sampled, it is ordinarily impossible to retain in the sample all the 
moisture that was in the delivered coal. Obviously, if it is desired 
to determine the amount of moisture in delivered coal, special mois¬ 
ture samples are usually necessary. Owing to the fact that a sample 
unavoidably loses moisture during every stage of handhng and 
preparation, the special moisture samples must be, in a sense, grab 
samples and must be collected, prepared, and placed in a sealed 
container with as little delay as possible. 

If a gross sample is collected during a period of a few hours or a 
very few days and the sample is collected and stored under conditions 
that will preserve its moisture content, a special moisture sample may 
be collected from the gross sample after it has been rapidly crushed, 
so that it will all pass through a 1-inch screen (the fineness to which 
the gross sample is reduced by the first crushing, see table on p. 25). 
It should be collected in a place comparatively cool and protected 
from rain, snow, wind, and the sun’s rays. A small scoop may be 
used for collecting the sample. The scoop should have a capacity 
of about one pound of coal—a scoop with bottom about 2J inches 
wide and 8J inches long and vertical sides about 2 inches high 
is about the right size. As the crushed coal is shoveled into a 
conical pile (p. 26), scoopfuls should be regularly and systematically 
collected so that approximately one scoopful will be collected to 
every two shovelfuls (about 30 pounds) deposited on the cone, 
thereby collecting a special moisture sample weighing from 30 to 
50 pounds. As the scoopfuls are collected they should be placed in 
a receptacle which can be tightly closed. After the gross sample has 
been formed into a conical pile (p. 26) and the special moisture sample 
weighing 30 to 50 pounds has been accumulated, the special moisture 
sample should be immediately and rapidly crushed so that no pieces 


22 METHODS OF SAMPLING DELIVERED COAL. 

of coal or impurities are larger than one-half inch; and it should be 
rapidly coned, flattened, and quartered, and a mailing can (p. 32) 
filled by taking portions from each quarter by use of the scoop (each 
portion only partly filling the scoop). The mailing can should be 
properly sealed at once (p. 36) and forwarded to the laboratory. 

If the gross sample in the above case is crushed mechanically and 
reduced to the quantity desired for transmittal to the laboratory by 
use of sampling machines in such a manner and in machines so 
designed that moisture losses are minimized, then the collection of a 
special moisture sample may prove unnecessary, as the moisture 
determination made on the regular sample will represent, within 
reasonable limits, the moisture content in the coal delivered. 

If a gross sample is collected during a period of several days, and if 
it is manifest that the sample will lose moisture during its storage 
and preparation, the special moisture sample should be accumulated 
by placing in a receptacle small iiortions of the freshly taken incre¬ 
ments making up the gross sample. Under these conditions it is 
desirable that a receptacle which can be hermetically sealed and has 
a capacity of about 100 pounds be provided in which to preserve the 
portions making up the special moisture sample as they are taken 
each day. After the gross sample is accumulated a quantity con¬ 
venient for transmittal to the laboratory should be selected from the 
special moisture sample (in accordance with the method given above) 
and forwarded in the mailing can, properly sealed for special moisture 
determination. 

If two or more railroad cars are to be represented by one gross 
sample, and if the cars contain different amounts of moisture seem¬ 
ingly in excess of the maximum moisture content guaranteed, mois¬ 
ture samples should be taken separately from each car. If a single 
gross sample is to represent several days’ delivery, and if because of 
heavy intermittent rains there is a considerable difference in moisture 
content between each day’s dehvery, and each contains moisture in 
excess of the maximum content guaranteed, then a special moisture 
sample should be taken representing each day’s delivery. Payment 
for the entire quantity on account of ash and B. t. u., ^^dry coal,” is 
determined from the analysis of the gross sample, but corrections on 
account of excessive moisture should apply to the particular car or 
cars, or day’s delivery. The purchaser would be at a disadvantage 
on account of heavy rain if corrections for moisture did not apply to 
each day’s delivery or fraction of the delivery, because if the special 
moisture samples were mixed, and one special moisture determina¬ 
tion only made, the effect of the heavy rains would largely be averaged 
out in the mixture, and, in addition, in storing, mixing, and reducing 
the samples there would be more or less moisture lost. 


DIRECTIONS FOR SAMPLING. 


23 


PREPARATION OF THE GROSS SAMPLE. 

TJio^igli a gross sample may he collected ever so carefully and may 
represent the coal sampled^ unless it is prepared in accordance with 
well recognized principles, the results of analysis and test may he worth¬ 
less for determining equitable settlement for the coal. 

The portions taken in making np the gross sample should he imme¬ 
diately placed in a box or a receptacle having a tight-fitting cover 
and a lock, for storage in order to preserve its integrity until it is 
reduced to a quantity convenient for transmitting to the laboratory. 

If it is desired to determine the moisture content of a gross sample 
that has been collected in a comparatively short time under pre¬ 
cautions to minimize moisture loss, the sample should be placed in a 
comparatively cool place and the crushing, mixing, and reduction 
for shipment to the laboratory should be done as rapidly as possible; 
this is imperative if the analysis of the sample is to represent the 
approximate condition of the coal with respect to its moisture content 
at the time it was weighed. Obviously, a sample on which a moisture 
determination is desired should be protected from rain and snow and 
strong air currents or winds and the sim’s rays during its storage and 
preparation. 

The proper preparation of a gross sample for shipment to the 
laboratory involves three operations: (1) Crushing, (2) mixing, and 
(3) reduction in quantity. The operations proceed in stages until 
the final sample is obtained. 

The crushing may be done by a mechanical crusher or by hand 
with an iron tamping bar or sledge on a smooth, clean, sheet-iron 
plate, of suitable dimensions, or on a solid floor—in the absence of a 
sheet-iron plate or smooth, tight floor, the crushing may be done on a 
heavy canvas—to prevent the accidental admixture of any foreign 
matter. The mixing and reduction may be done by hand with a 
shovel, or mechanically by means of riffles or sampling machines. 

It is obvious that if the gross sample is reduced in quantity without 
crushing, the effect of the selection or rejection of one or more of the 
large pieces of slate or other impurities in the portion of the sample 
retained multiplies rapidly as the sample becomes smaller. To illus¬ 
trate: A sample of 1,000 pounds contains a piece of slate weighing 
1 pound, which is one-tenth per cent of the weight of the gross sample. 
If the sample is halved in quantity without crushing, the half of the 
sample retained for further reduction w’^ill contain two-tenths per cent 
ash more or less than the rejected half, according to whether the 
piece of slate went into the retained half or into the rejected half. In 
halving the 500-pound sample, the 1-pound piece of slate would have 
an effect of four-tenths per cent on the ash content of either the re¬ 
tained or rejected half. If, in continuing the reduction of the sample 
67500°—Bull. 116—18-4 


24 


METHODS OF SAMPLING DELIVERED COAL. 


by halving each time, the 1-pound piece of slate by chance sliould 
fall into the retained hah on each successive halving, it would have 
an effect of 12.8 per cent on a 7 }-|-pound sample—that is, in halving 
the 15|-pound sample the 1-pound piece of slate would cause the ash 
content of one-half of the sample to be 12.8 per cent higher than the 
other; in other words, if the average ash of the coal is 10 per cent, 
one of the 7y|-pound samples would show an ash content of 22.8 
per cent. This fundamental principle that the weight of the largest 
piece of impurities should be relatively very small in ratio to the 
weight of the sample at each halving is recognized in the instructions 
for sampling issued by the Bureau of Mines, which specify that the 
sample should be successively crushed, mixed, and reduced. 

In the sampling of ores it is recognized that the particles of ore 
must be crushed to varying degrees of fineness in order to obtain 
results within an aUowable limit of error, and to accomplish this, 
elaborate and costly plants are constructed and maintained. Brun- 
ton ® states that experiments and calculations and a general con¬ 
sideration of the subject indicate that the size to which ore must 
be crushed for sampling in order to reduce error within an allowable 
limit will depend on: 

1. The weight or bulk which the sample is to have. Evidently the smaller the 
sample the finer the material must be crushed. 

2. The relative proportion between the value of the richest mineral and the average 
value of the ore. If the average grade of the ore is high in comparison with the grade 
of the richest mineral, a particle of richest mineral of a given size and value will have 
less percentage effect on the sample than the same particle would have on the same 
amount of lower-grade ore; therefore, other conditions being the same, with high- 
grade ores we may crush more coarsely than with low-grade ores and still keep within 
the same percentage of error; while if the richest mineral is of comparatively high 
grade a particle of it of given size will have a greater effect on the sample than if it is 
of low grade, and this will necessitate finer crushing. 

3. The specific gravity of the richest mineral. The higher the specific gravity 
of the richest mineral the greater the value contained in a particle of given size and 
grade, and hence the gi'eater the influence of such particle on the sample; from which 
follows the necessity of keeping down the size of the largest particles by finer crushing 
than is required when the richest mineral is of lower specific gravity. 

4. The number of particles of richest miiperal which are likely to be in excess or 
deficit in the sample is evidently an important factor, a liability to a large number 
necessitating especially fine crushing. But such liability can result only from imper¬ 
fect mixing, and for material mixed with average thoroughness this number must be 
small. 

And in conclusion this paper further states that: 

The results of the investigations recorded in this paper show how absolutely neces¬ 
sary it is that ore samples should be recrushed after each successive ‘ ‘ cutting down ’’ so 
that as the sample diminishes in weight there may be a nearly constant ratio between 
the weight of the sample and that of the largest particle of ore contained therein. 

O Bjunton, D. W., The theory and practice of ore-sampling, Trans. Am. Inst. Min. Eng., 1895, vol. 25. 




DIEECTIONS FOR SAMPLING. 


25 


In applying these principles to coal, slate and other impurities are 
to be considered as taking the place of the ‘‘richest mineral,’’ but, 
as coal is a low-priced commodity, the cost of collecting and pre¬ 
paring samples must necessarily be correspondingly small, making 
the installation and operation of elaborate sampling plants prohibitive. 

Though the fineness to which the Bureau of Mines specifies that 
samples be crushed may not be strictly in accordance with the 
fineness that would be necessary for theoretically accurate reduction 
of the samples, and as coal of a definite physical character and 
composition would require special treatment, the fineness specified 
in the table below, it is believed, will give results that are fairly 
representative. 

When prepared by hand the pieces of coal and impurities should 
be crushed to sizes not greater in any dimension than the sizes indi¬ 
cated in the following table before each reduction of the sample 
into two approximately equal parts: 

Size of coal and quantity required for each reduction. 


Weight of sample 

Largest size of coal and impurities allowable in sample before division. to be divided, 

pounds. 

One inch. 1,000 or more. 

Three-quarters of an inch. 500 

One-half inch. 250 

Three-eighths of an inch. 125 

One-quarter of an Inch. 00 

Three-sixteenths of an inch, or 4-mesh screen. 30 


Diagram showing the treatment of a 1,000-pound sample. 

1,000-pound gross sample, crush to 1-inch mesh; mix by coning and 
long-pile method; halve by alternate shovel method. 


500, 

500 pounds, crush to f-inch mesh; mix by coning and long-pile 
' method; halve by alternate shovel method. 

250, 

250 pounds, crush to ^-inch mesh; mix by coning method; halve by 
' quartering method. 

125, 

125 pounds, crush to f-inch mesh; mix by rolling on blanket; halve 
' by quartering method. 

62i, 

62^ pounds, crush to f-inch mesh; mix and halve by blanket and 
' quartering method. 

31h 

31f pounds, crush to j^-inch or 4-mesh; mix and halve by blanket 
' and quartering method. 

15f' 

^ 15f pounds; mix and halve by blanket and quartering method. 


•-^711 pounds. 

Fill 5-pound container and mail to laboratory. 


7|| pounds. 

Fill 5-pound container 
for reserve sample. 



















26 METHODS OF SAMPLING DELIVERED COAL. 

Care should ho exercised to crush finely pieces of foreign matter 
before each reduction so that the crushed impurities can be distributed 
through the sample, and when crushing to keep pieces of slate and 
other impurities from flying out of the sample. In crushing the 
coal on wood, brick, cement, or on floors of such materials, sphnters 
or small fragments may be broken from the floor and bo mixed 
with the sample. Such floors, if used, should be thoroughly clean 
and free from cracks. If a sheet-iron plate is used, it should be free 
from rust. 

After each crushing the sample should be thoroughly mixed before 
reduction in quantity. The method which gives generally satisfac¬ 
tory results is as follows: 

The crushed coal is formed into a conical pile by depositing each 
shovelful of coal on top of the preceding one (see PL I, A, which 
shows approximately 1,100 pounds of coal crushed to 1-inch mesh 
and finer, properly coned.) As the shovelfuls are deposited the fine 
material forms the apex of the cone, while the coarse particles roll 
down toward the base. By walking around the cone and system¬ 
atically depositing shovelfuls on the apex of the cone from every 
side, care being taken to maintain the original form, the sampler will 
properly distribute the fine and coarse coal. A new, long pile is then 
form*cd by taking a shovelful at a time (as the sampler fills the shovel 
he should walk around the cone, thus systematically removing the 
coal from the base of the cone) and spreading it out in a straight 
line or ribbon the width of the shovel; the length is 5 to 10 feet for a 
shovel holding about 15 pounds. Each new shovelful is spread over 
the top of the preceding one, beginning at opposite ends, and so on 
until all the coal has been formed into one long pile. (PI. I, B, 
shows the coal of the cone formed into a long pile.) The sample is 
then halved in quantity by shoveling the long pile to one side, 
alternate shovelfuls being discarded while the retained shovelfuls 
are formed into a new cone. In shoveling the coal from the long 
pile the sampler takes the shovelfuls of coal systematically around 
the pile, advancing at each shovelful a distance about equal to 
the width of the shovel, thereby preserving the symmetry of the 
form of the pile. If the pile should be reduced by shoveling all of 
the coal from either end, and if the alternate shovelfuls discarded 
contained coal mainly from the sides of the pile, the rejected half 
of the sample would contain a preponderance of coarse coal, while 
the retained half would contain relatively too much fine coal. This 
is because the coarse coal rolls down the sides of a pile or cone while 
the fine coal builds up, so that the relative proportions of coarse 
and fine coal in outer and inner portions of the pile are quite different. 
The alternate shovelfuls of coal which are retained are formed mto 


a new cone. 


BUREAU OF MINES 


BULLETIN 116 PLATE I 




B. CRUSHED GROSS SAMPLE REMIXED IN LONG PILE. 



AXIS OF CONE 


C. REDUCED SAMPLE QUARTERED. 





















DIRECTIONS FOR SAMPLING. 27 

In conmg care should be observed to deposit each shovelful so that 
the center of the cone as started will not be drawn to one side for in 
quartering a cone the center of which has been drawn, two opposite 
quarters will contain an excess ratio of fine material, while the other 
two quarters will contain a deficiency. This will be apparent when 
it is considered that when a cone is formed, the fines build up the 
apex while the coarse particles roll down the sides. In ore sampling 
this may be of especial importance, as the fines are generally the 
richest ore, and as a result the metallic content of the final sample 
will be more or less than the average of the original pile, dependino- 
upon which two quarters are retained. D. W. Brunton, in a paper 
entitled “Modern Practice of Ore-Sampling,” « shows by illustrations 
and an example the effect of “drawing the center.” He takes as an 
example the reduction of a 2,000-pound lot of ore to 62J pounds 
(requiring quartering five times), and supposing that at each stage 
the sample taken represented 98 per cent of the actual value of the 
cone, he shows that the final sample would only give 90.3 per cent of 
the true value of the cone. 

After the gross sample has been reduced by the coning, long-pile, 
and alternate shovel methods to approximately 250 pounds, the 
sample is further reduced in quantity by the quartering method. 
Before each quartering, the sample is thoroughly mixed and made 
into a conical pile, as follows: 

Quantities of 125 to 250 pounds are shoveled into a new conical 
pile by depositing each shovelful of coal on top of the preceding one; 
quantities less than 125 pounds are placed on a suitable cloth, 
measuring about 6 by 8 feet, and mixed by raising first one end of 
the cloth and then the other, rolling the coal back and forth. After 
the coal is thoroughly mixed it is formed into a conical pile by 
gathering together the four corners of the cloth. The conical pile 
is quartered as follows: 

The cone is flattened, its apex being vertically pressed down with a 
shovel or a board, so that each quarter contains the material originally 
in it. The flattened mass, which should be of uniform thickness and 
diameter, is then marked off into quarters with a board held edgewise, 
or a piece of sheet iron, along two lines that intersect at right angles 
directly under the apex of the original cone. The diagonally opposite 
quarters are shoveled away and discarded, and the spaces which they 
occupied brushed clean (PI. I, 0 , shows the four quarters and the 
intersecting lines; quarters 1 and 3 will be rejected). The coal 
remaining is successively mixed, coned, and quartered on the canvas 
until two opposite quarters are about equal to the quantity (approxi¬ 
mately 5 pounds) required to fill the sample container for shipment 


a Am. Inst. Min. Eng., vol. 40, p. 571, presented at the Spokane meeting, September, 1909. 



28 


METHODS OF SAMPLING DELIVERED COAL. 


to the laboratory. If after two opposite quarters are placed in the 
sampling container, it is found that the container is not compactly 
filled, the other two quarters should be mixed, coned, flattened, and 
quartered, and the remaining space in the container then filled by 
taking equal segments from opposite quarters, using the sampling 
scoop (p. 21). The two rejected quarters are not thrown into the 
discard, but are placed in a sampling container, hermetically sealed, 
and held in reserve at the delivery point until report of analysis of 
the regular sample is received and settlement made for the coal. 

The operations and methods followed in preparing and reducing 
the gross sample to a quantity convenient for transmittal to the 
laboratory are diagrammatically shown on page 25. The treatment 
of the 5-pound sample when it is received by the Bureau of Mines is 
diagrammatically shown on pages 34 and 35. 

Accuracy in reducing the gross samples requires that the coal be 
crushed as directed, thoroughly and systematically mixed, formed in 
piles, and accurately divided, either by the alternate-shovel method 
or by quartering, so that the rejected portions and the retained por¬ 
tions will be uniform in character and weight. Thorough cleanliness 
must be maintained during the entire operation. 

The method of coning and quartering coal and the principles which 
must be recognized are in essential features as given by Richards ® for 
reducing ore samples. 

Whenever the different increments of samples are collected through¬ 
out some considerable period of time, each increment may be crushed 
as soon as taken, and the pieces of coal and impurities may be broken 
sufficiently small to permit two or more reductions of the accumu¬ 
lated samples before further crushing is necessary. 

If deliveries extend over a considerable period, what would other¬ 
wise be a gross sample may be worked down, as it accumulates, in 
successive stages to quantities of a size suitable for transmittal to 
the laboratory, and these fractional samples may be analyzed and the 
several analyses averaged, or they may later be mixed (at the delivery 
point or in the laboratory and reduced to one sample) and one analysis 
made. In averaging analyses or in mixing the several samples, 
weights should be used in proportion to the tonnages that the frac¬ 
tional samples represent. 

If the contract amounts to a considerable quantity, necessitating 
several samples in relatively short periods, the installation of a 
crusher has been found in some cases expedient and economical for 
reducing the gross samples to three-sixteenths inch mesh, or finer, and 
in such case, instead of the mixing and reducing being done by hand, 
the reducing buckets or mixing and reducing machine shown in Plate 
II are used. Even though the contracts are relatively small and 


Richards, R. H., Ore dressing, vol. 2, p. 844, and vol. 3, pp. 1574-1578. 



BUREAU OF MINES 


BULLETIN 116 PLATE II 




B. MIXING AND REDUCING MACHINE 












DlRECTIOlSrS FOR SAMPLING. 


29 


the samples are crushed by hand, the use of the reducing bucket or 
machine is recommended. These devices are generally used after the 
gross sample has been mixed and has been reduced by the ''alternate 
shoveP' and quartering method to about 60 pounds. 

After the gross sample has been reduced to less than 250 pounds, a 
shovel takes too large a proportion of the coal, making further reduc¬ 
tion by alternate shovelfuls unreliable. The quartering method is 
used after the sample has been reduced by alternate shovels to 
approximately 250 pounds, as the capacity of an ordinary shovel is out 
of proportion to the size of the sample. It may prove desirable in 
samphng coal containing considerable quantities of free impurities of 
uneven size to use small shovels of 10 pounds and less capacity in 
reducing the gross sample by alternate shovels, for as the size of the 
shovel is diminished the number of fractional parts into which the 
sample is divided is increased. As the sample becomes smaller, 
greater precision in quartering is required, and, consequently, refine¬ 
ments in the manner of mixing and reducing should be introduced. 
The use of buckets or the machine makes thorough mixing possible 
and the riflies insure accurate division. 

A mechanical crusher and mechanical means for preparing the 
samples for transmittal to the laboratory may be installed and the 
collection and preparation of the sample can then be made a con¬ 
tinuous and purely mechanical process. When mechanical crushers 
are used the sample should be inspected before or while being fed 
to the crusher to make certain that the sample does not by chance 
contain a piece of iron, such as a tie spike or some other highly abra¬ 
sive substance, accidentally loaded with the coal in the mine and 
undetected in collecting the sample, otherwise the abrasion of the iron 
may introduce errors which would alter appreciably the final results. 

As it is so important that samples shall be carefully and system¬ 
atically prepared by a prearranged plan, in order that their analyses 
will serve as an equitable basis for the determination of the price 
to be paid for coal purchased under the specification method, the 
specifications used by the Government give the method of sampling, 
as described above, in considerable detail. To assure its being 
clearly understood the method of sampling specified in a contract 
may be illustrated. The instructions which accompany the specifica¬ 
tions given on pages 46 to 58 have been illustrated (PI. V) to show 
the hand preparation of samples. 

SAMPLING BUCKETS. 

When the samphng buckets are used, two similar ones are required. 
About half of the top of each bucket is covered with a riffle. The 
coal is placed in one of the buckets, and the projections aa' (PI. Il, 
A) of the stiffening rod of this bucket are placed in the notches hV 


30 


METHODS OF SAMPLING DEIJVEKED COAL. 


of the second bucket. The coal that is poured from the first bucket 
flows to the riffle of the second bucket; every alternate section cut 
out by the riffle is discarded and the other sections are caught in 
the second bucket, thus halving the sample. The sample is poured 
from one bucket to the other until it is reduced to about 5 pounds, 
but the discarded 5-pound half is placed in a container and kept as 
the reserve sample.® 

THE MIXING AND REDUCING MACHINE. 

If more thorough mixing than can be done with the buckets is 
desired, the mixing and reducing machine is used. Plate II, B, shows 
the apron of the cylinder of this machine open for receiving a sample. 
After the sample is poured in, the apron’s position is shifted, a being 
moved to a'. The cylinder is then closed and revolved counter¬ 
clockwise. The closed sides of the riffles plow through and thor¬ 
oughly mix the coal, and no coal can be discharged through the riffle 
while the cylinder is revolved in this direction if the level of the coal 
is below the axis of the cylinder. After the sample has been mixed, 
the cylinder is rotated one turn clockwise; the coal in the cylinder is 
then cut by the planes of the riffle and half of it is discharged into the 
receiving tray. The coal remaining is again mixed by revolving the 
cylinder counterclockwise. By alternately changing the direction of 
rotation, the coal is alternately mixed and halved until about 10 
pounds remain in the cylinder. The tray is then emptied of the dis¬ 
carded coal and the 10-pound sample mixed and halved, and the 
5-pound sample caught in the tray is put in a container and becomes 
the official sample while the 5-pound sample remaining in the cylinder 
is put in a container and held as the reserve sample. The interior of 
the machine is easy of access and should be brushed clean after each 
sample. 

Generally speaking, the use of mechanical means for sampling coal 
and preparing samples gives more reliable and satisfactory results 
than hand labor, as the personal equation is partly eliminated. 

COLLECTION OF SAMPLES IN THE DISTRICT OF COLUMBIA. 

Gross samples are collected from deliveries under Government 
contracts in the District of Columbia in accordance with the method 
given in the specifications and as set forth in this paper. Instead of 
the gross sample being reduced to 5 pounds, as is necessary in the 
case of deliveries elsewhere, the sample, after it is reduced to 125 to 
250 pounds, is placed in galvanized-iron buckets, each large enough 
to hold about 70 pounds of coal and having a close-fitting lid that can 
be locked. The locked buckets of coal are immediately delivered 
to the crushing room in the Bureau of Mines building, where the 
preparation of the sample for the laboratory is continued. 

a Buckets of this type are a rapid and reliable means of reducing samples. The riffles of the buckets 
first developed were of galvanized iron. Difficulty in having these riffles skillfully made and the frequent 
repairs from rough usage indicate that buckets made of steel plates and channel irons would piove more 
serviceable. 



COLLECTION OF SAMPLES IN THE DISTRICT OF COLUMBIA. 31 


THE SAMPLING ROOM. 


For preparing the samples collected in Washington, after they have 
been reduced at the dehvery point to 125 to 250 pounds, specially 
designed machinery is installed in the samphng room of the Bureau 
of Mines plant. The samples are put through a motor-driven ham¬ 
mer crusher which crushes the coal to pass a A -inch mesh screen. 




The Bureau of Mines receives from time to time requests from dif¬ 
ferent branches of the Federal service for suggestions as to the type 
and design of installations for crushing and reducing coal samples. 
Plate III, A, is a view of a simple coal-samphng plant that is largely 
used by the Bureau of Mines and has been adopted by other bureaus 
and establishments of the Government. Figure 1 shows the design 
G7590°—Bull. 116—18-5 

































































32 


METHODS OF SAMPLING DELIVERED COAL. 


of this plant. The riffle is constructed of channel irons and steel 
plates bolted together. The plan and sections of the riffle are shown 
in working drawings constituting figure 2. The numbers assigned to 
the parts shown in this figure are also shown in Plate IV, A. A hst 
of the parts used in the riffle, giving the number of each required, 
follows: 

List of parts used in riffle for reducing coal sample. 


Piece 

No.o 

Material. 

Number 
of pieces 
required. 

1 

^-inch steel plate. 

9 

2 

.do. 

4 

3 

.do. 

2 

4 

f-inch channel, 41 inches long. 

12 

5 

|-inch steel rod, 10^ inches long . 

4 

6 


12 

7 


1 

8 

|-inch by 2-inch flat steel, 2 feet 2 inches long. 

2 




a See fig. 2 and Pi. IV, A . 


The hopper, bin, and other parts through which the coal is passed 
are made as dust proof as possible and iron cement is used to close 
leaks. However, more or less free dust arises from the crusher. In 
the Bureau of Mines sampling plant this dust is carried away by 
means of a ventilating system, there being an exhaust fan, driven by 
a direct-connected motor, in a penthouse on the roof of the budding. 
Galvanized-iron ducts lead from the fan to the laboratory and sam¬ 
pling rooms. In the sampling rooms, leading from the main venti¬ 
lating duct, are branches connecting each bin and hopper, some with 
hoods placed over dust-producing machines. On each one of these 
branch ducts, as well as on the main ventilating pipe, dampers are 
attached by which the draught is regulated. The system is very sat¬ 
isfactory. It keeps the sampling rooms free from dust and prevents 
any from entering other parts of the building. 

The sample is received in buckets, each holding approximately 70 
pounds of coal, and the filled buckets are stored on the platform. 
Each bucket of coal making up the sample is successively passed 
through the motor-driven crusher, which reduces the coal to -j^-inch 
mesh and finer (practically all of the coal will pass through J-inch 
mesh), and the coal is halved by a riffle, one half being deflected to a 
i bin for discarded coal and the other half into a bucket. As the 
, buckets are emptied into the crusher, they are available for catching 
the retained half from the riffle. Buckets containing the half of 
the sample are easily swung to the platform and the sample is again 
halved in quantity by dumping the coal through the trapdoor (shown 
in fig. 1) and repassing it over the riffles. Elevating the sample to 
the platform and halving the sample are repeated until the sample is 
reduced to the quantity convenient for transmittal to the laboratory. 



















BUREAU OF MINES 


BULLETIN 116 PLATE III 



A. COAL-SAMPLING PLANT. 



B. DOUBLE CONTAINER, a, PAPER CASE; b, b', SECTIONS OF WOODEN BOX; c, CONTAINER 
ASSEMBLED; d, HOLE FOR RELEASING CATCH. 
















BUREAU OF MINES BULLETIN 116 PLATE IV 





SAMPLING RIFFLE. B. SEALING CONTAINER. 












COLLECTION OF SAMPLES TN THE DISTRICT OF COLUMBIA. 33 


Only the relation of one bin wall to the riille is shown in the drawing; 
the shape of the bin can be varied to suit the arrangements in the 
building. If the building in which the installation is housed is so 
situated that a chute for the discarded coal can lead directly into 
a wagon body, car, or the boiler room, the disposal of this coal will 
be simplified. 




For the inspection of the rilTle and the removal of matter clogging 
the riflle, a small door is provided in the main hopper. After each 
crushing the hopper and rillle should be brushed clean. 

This particular form of equipment was developed with a view to 
simplicit}^ and cheapness. By placing a series of rillles one below 






































































































































































































34 


METHODS OF SAMPLING DELIVERED COAL. 


the other, the sample can be reduced to one-quarter, one-eighth, 
one-sixteenth, etc., of its original quantity, depending upon the 
number of riffles installed. As more riffles are added, the cost is 
increased and the platform must be raised, requiring other means 
than hand labor for elevating the parts of the samples. The Bureau 
of Mines is experimenting with other devices and types with a view 
to increasing the efflciency of the installation so that it will accurately 
select fractional parts of the gross sample with a minimum of 
handling and at a relatively low cost. 

All samples are reduced to a quantity that will nearly fill a 5-pound 
container. The samples are then in the same stage of preparation 
as those received from points outside of Washington, and like them 
are further prepared in the sampling room.® The methods of 
preparation are diagrammatically shown in the following: 

Diagrams shoiving treatment of the 5-pound sample in the laboratory. 

METHOD A. 

5-pound sample crushed by roll crusher to 20-mesh. 



5 pounds, less 3 ounces. 

i ■ 
i 

I 


3 ounces immediately placed in rubber- Successively passed through riffles and 

stoppered bottle for total moisture de- reduced to about 6 ounces. Rejected 
termination only. coal returned to the container and held 

-as reserve. 


6 ounces. 


6 ounces ground by planetary-disk crusher to 60 mesh, passed through riffle, 3 ounces' 
returned to reject and 3 ounces placed in a rubber-stoppered bottle. (This is the 
laboratory sample proper.) 


1 gram (about 
ounce). 


1 gram. 


For moisture in 
laboratory sam¬ 
ple. 


Ash in this 1-gram 
sample deter¬ 
mined after the 
moisture is de¬ 
termined. 


For volatile-mat¬ 
ter determina¬ 
tion. 


I 1 gram. 


Sulphur determi- 
nation by 
Eschka method. 


i 1 gram. 


For heating-value 
determination in 
a bomb calorime¬ 
ter. 

i 

^ 


Sulphur is deter¬ 
mined o n the 
washings and 
residue from the 
calorimeter after 
combustion. 


a The method of preparation of the samples in the sampling room, with a description of the laboratory 
methods and equipment, is given on pp. 74 to 91, Bureau of Mines Bulletin 41. 



























SEALING AND MAILING. 


35 


Diagrams showing treatment of the 5-pound sample in the laboratory —Continued. 

METHOD B. 

5-pound sample dried in air-drying oven for “total moisture” determination. 

I 


Crushed by rolls to 20 mesh. 


Reduced in quantity by riffles to 8 ounces. Rejected coal returned to the container 

and held as reserve. 

^i 

8-ounce sample pulverized to 60 mesh in Abbe ball mill. 


8-ounce sample reduced in quantity by riffles to 3 ounces which is placed in a rubber- 
stoppered bottle and becomes the laboratory sample proper. Rejected coal returned 
to the container and held as reserve. 

I 

3-ounce laboratory sample treated the same as the 3-ounce sample under method A. 


Both methods of procedure given above are followed in the Bureau 
of Mines laboratory in Washington, D. C., wherein the samples repre¬ 
senting Government coal deliveries are analyzed and tested—method 
B being followed for most anthracite samples and for any samples of 
high-moisture or wet coals, as by this method a more representative 
moisture value can be obtained than by method A., for in method A 
high-moisture or wet coals unavoidably lose more or less moisture m 
the crushing of the 5-pound sample. Method B, somewhat modi¬ 
fied,® is followed on all samples in the Bureau of Mines laboratory in 
Pittsburgh, Pa., which is maintained for analyzing and testing sam¬ 
ples necessary for the conducting of certain fuel, mining, and metallur¬ 
gical investigations which the bureau is making. 

SEALING AND MAILING. 

The final 5-pound sample is immediately placed in the container 
furnished by the Bureau of Mines and sealed air-tight. The coal 
should be firmly packed in the container, so as to occupy as much of 
the space as possible, as in this way the air is more nearly excluded. 
This packing is best accomplished by having the coal finely crushed 
in the manner described in the preceding pages and by shaking or 
jarring the container repeatedly and vigorously while filling it. 

a Stanton, F. M., and Fieldner, A. C., Methods of analyzing coal and coke: Tech. Paper 8, Bureau of 
Mines, 1913, 42 pp. 

















36 


METHODS OF SAMPLING DELIVERED COAL. 


Two coal-sample containers have been developed by the Bureau 
of Mines, one a galvanized iron can and the other a double container, 
consisting of a wooden shipping box and an inclosed pressed-paper 
case. 

The metal can is 11 inches long and SJ inches in diameter (inside 
dimensions), with a screw cap 2 inches in diameter. Its edges are 
crimped and carefully soldered, so as to make it air-tight and strong. 
The screw cap has a washer of rubber, or other flexible material, to 
exclude the air. As a further protection and to insure tightness, 
the cap, when in place and screwed down, is wrapped carefully with 
several layers of adhesive tape, the first layer of winch completely 
covers the joint between the lower edges of the cap and the neck of 
the can. In Plate IV, B, a shows the first layer of the tape being 
forced down with thumb and forefinger, and h, the can properly 
sealed. It is not advisable to use solder, paraffin, or sealing wax 
of any kind, because some of the material may become mixed with 
the coal, either when it is applied or when the cap is removed. Before 
it is filled, each can should be carefully inspected as to tightness and 
freedom from rust. 

The capacity of the can is 2 J to 3 pounds of coal, and as the quan¬ 
tity required for transmittal to the laboratory is 5 pounds, two of 
the cans are used for each sample. After the sample has been reduced 
to a quantity that wiU about fill two cans, it should be thoroughly 
mixed and divided into two parts and one put in each can. Bureau 
of Mines Form 6-220, used for furnishing data concerning the sample 
(p. 38) is filled in for each can, and the form is placed (not pasted) 
around the can. Each form shows the number of the can which 
carries the other half of the sample. As a safeguard against the can 
opening in transit and the coal damaging the contents of a mail sack, 
each can is wrapped with several thicknesses of heavy manila paper. 
An addressed franked wrapper is pasted on or tied around the 
wrapped can. 

The double container is shown m Plate III, B, in which a is the 
pressed ‘^damptite’’ paper case, W the two sections of the wooden 
box; c is the container assembled. 

The box is opened by inserting a nail, or any pointed instrument, 
in the two holes in opposite sides of the box (one being shown, d). 
This pointed instrument should not be inserted too far, as it would 
perforate the paper case, but only far enough to release the spring 
catches which hold the two halves of the box together, so that the 
upper half of the box can he lifted off. 

The pressed paper case is 5f inches total diameter and 7 inches lo ng 
over all, and has a capacity of 5 to 7 pounds of coal. The shipping 
box is made of sound, well-seasoned basswood, free from knots, 
checks, and doaty places, and is made strictly in accordance with 


SEALING AND MAILING. 


37 


specifications, as regards thickness of the material, number of nails, 
inside dimensions, arrangement of corners, catches, finish, etc. The 
corners are made lock-jointed, each being glued throughout its full 
length by dipping the joints in glue before assembling. They are 
further reinforced by small finishing nails driven through the tenons 
of each corner, so that the box is thoroughly substantial. One part 
of the box has two corner blocks of specified dimension and form, 
which are glued through their length into the corners of the box and 
riveted. Two special suit-case catches are used, which are placed on 
the inside of the box near opposite corners and so situated that they 
will operate in either of the two possible ways of assembling the 
box. The small holes are so drilled through each side of the box and 
through the small part of the catch lug that the catches are readily 
released when a pointed instrument is inserted in the holes. 

The sample of coal is placed in the paper case, and the edge of the 
cap is wrapped with electrician adhesive tape so as to seal the paper 
case as nearly air-tight as possible. Form 6-220, properly filled in 
with data concernmg the sample, is placed (not pasted) around the 
case, and the case is then placed in the box and the box assembled. 
An addressed shipping tag is pasted or tacked onto the box. 

The blank form referred to is in two sections—an original and a 
duplicate. The original form accompanies the sample, furnishes 
the bureau complete information as to the sample, and becomes the 
bureau’s permanent record. The duplicate is used as a file copy 
for the office submitting the sample. 

Special attention should be given to filling out the form and 
promptly forwarding the sample. Failure to fill out the form 
properly or to place it around the container may cause indefinite 
delay in making the analysis of a sample and in reporting the results. 

A letter should be written informing the bureau that a sample or 
samples (container numbers stated) have been forwarded. As the 
tonnage on many orders or deliveries during a month may be consid¬ 
erable, and as samples may be submitted from time to time, unless the 
bureau is informed it has no knowledge whether all samples have 
been received to represent the tonnage, nor has it any intimation as 
to which is the first or last sample, although this information is 
necessary to insure prompt reports. To furnish the necessary 
information, it should be stated in the letter, as follows: 

This is the first and only sample which will be submitted on order No.-, or of 

the deliveries during the month of-. 

Or, 

This sample is the-(give number) one submitted on order No.-, or of the 

deliveries during the month of-, and other samples on this order or mouth’s 

delivery will be submitted. 




38 


METHODS OF SAMPLING DELIVERED COAL. 


Or, ^ 

This is the last sample on order No. -, or of the deliveries during the 

month of-, and is to be considered with samples submitted in containers 

numbered-. 

If a sample is submitted representing coal from a mine or from a 
source other than that specified in the contract, the letter transmitting 
the sample should so state, in order that the records of the Bureau of 
Mines will be complete. 

A copy of the front and reverse sides of the two sections comprising 
the form mentioned above are herewith given. 

lOriginal, front.] 

6-220 DEPARTMENT OF THE INTERIOR. 


BUREAU OP MINES. 


Coal delivered to. 

(Institution. If ship or barge, state where loaded.) 

Container number.Sample number. 

(Serial number of institution.mailing sample.) 

Name of contractor... 

Coal, kind and size. 

Number of tons represented by this container. 


Date of delivery. Date of mailing sample. 

Contract number. Order number 


Is this the only sample on this order or month’s delivery?. 

(Answer yes or no.) 

If not, is this the first, second, etc., or last sample?. 

If this is the last of several samples, state total tonnage delivered under this order 

or month’s delivery.tons. 

Original. (Signed). 


[Original, back.] 

SUGGESTIONS AS TO FILLING AND SEALING CONTAINERS. 

The coal sample should be firmly packed in the container so as to occupy as much 
of the space as possible, since in this way the air is more nearly excluded. Tp insure 
the tightness of the container, the cap when in place should be wrapped carefully 
with several layers of adhesive tape, the first layer of which should completely cover 
the joint between the lower edge of the cap and the neck of the container. It is not 
advisable to use solder, paraffin, or sealing wax of any kind, because some of the mate¬ 
rial may be mixed with the coal either when the material is applied or when the cap 
is removed. Before being filled each container should be carefully inspected as to 
tightness and freedom from foreign matter. Any containers rendered defective 
in transit should be returned empty. The Bureau of Mines will furnish a supply 
of containers and of this form on request. 



















COAL SPECIFICATIONS AND PROPOSALS. 39 

[For instructions as to use of this form, see instructions on back of attached (^tuplicate) section.] 

[Duplicate, front.] 

3 DEPARTMENT OF THE INTERIOR. 


BUREAU OF MINES. 


Coal delivered to 


(Institution. If ship or barge, state where loaded.) 

Container number. Sample number. 

(Serial number of institution mailing sample.) 

Name of contractor. 

Coal, kind and size. 

Number of tons represented by this container. 

Dates of delivery. Date of mailing sample. 

Contract number. Order number. 

Is this the only sample on this order or month’s delivery?. 

(Answer yes or no.) 

If not, is this the first, second, etc., or last sample?. 

If this is the last of several samples, state total tonnage delivered under this order or 


month’s delivery.tons. 

Duplicate. (Signed). 


[Duplicate, back.] 


INSTRUCTIONS AS TO THE USE OF THIS FORM. 

Fill out this form for each sample of coal forwarded to the Bureau of Mines. The 
office filling out the form is to retain the duplicate copy. The original must be placed 
around the container (but not pasted to the container; it may be held in place by a 
rubber band) in such a manner that the sample and the information regarding it can 
not be separated in mailing. This form must be properly filled out and forwarded 
in order to expedite testing and reporting. A letter should be written informing the 
bureau that sample or samples (giving container numbers) have been forwarded. 
The receipt of the sample will be immediately acknowledged. 

[For suggestions as to filling and sealing containers, see back of attached (original) section.] 


REPORTING ANALYSES. 

The analyses and tests of samples are reported hy the laboratory to 
the fuel-inspection section, where the record of the samples is kept. 
The laboratory receives the samples with an identification number 
only, which is given the sample when the sample is received from the 
mail, and the laboratory reports the analysis and test by number 
only. If a report is to be based on the analyses of two or more sam¬ 
ples, the analyses are averaged, each analysis being given a weight 
according to the proportion of the total tonnage which it represented. 
The results are then reported in triplicate on the following letter 
form to the branch of the service submitting the sample or samples, 
which in turn furnishes the contractor one of the copies: 
















40 


METHODS OE SAMPLING DELIVERED COAL. 


DEPARTMENT OF THE ^INTERIOR. 

BUREAU OF MINES, 

Washington, D. C., . 

Sir: In reference to the.tons of. 

coal delivered on your contract No.and your order 

No.to the. 

.,191 , by.. 

The analysis of the samples of coal received by the Bureau of Mines was as follows: 



As received. 

Dry coal. 

^loisture. 



Volatile matter. 

Fixed carbon. 

Ash. 

Total. 



Sulphur. 

British thermal units. 



This information is for the use of the Government and the dealer or operator furnishing the coal. It i 
confidential until it is published by the United States Government. 


Remarks: 

Certified: Respectfully, 

Engineer in charge Fuel Inspection. Director. 

COAL SPECIFICATIONS AND PROPOSALS. 

There are given in the following pages coal specifications and pro¬ 
posals typical of those in use by the Government for the purchase of 
coal under specifications based on the heating vaiuej the content of 
ash and of moisture, and other considerations. 

The method for samphng ® is not printed as an integral part of the 
specifications, but as a separate appendix. It is published in a larger 
edition than the specifications, so that all officials charged with the 
duty of collecting samples may be supplied with copies. 

Two classifications of the coal purchased are made, namely, {a) 
coal for steam power and heating plants, which include bituminous 
(semibituminous, subbituminous, lignite) and the small sizes of 
anthracite (pea and buckwheat), and {h) the large sizes of anthracite 
(broken, egg, chestnut, and stove), which are used in small house¬ 
heating furnaces and stoves for heating and domestic uses. 

The purpose of the specifications is to clearly set forth the char¬ 
acter and quality of coal desired, to obtain bids which fuTly specify 

a The Government method of sampling coal is quite similar to the tentative standard method of the 
American Society for Testing Materials (Am. Soc. Testing Materials: Yearbook, 1915, p. 591). 





























COAL SPECIFICATIONS AND PROPOSALS. 


41 


the coal offered, the values offered in the case of power and heating 
coals by the successful bidder becoming a part of the contract, to 
furnish means whereby the Government may he assured of receiving 
the coal contracted for, providing for a definite procedure for 
determining equitable settlement for coals differing in character and 
quality, and to include concise statements of the necessary legal 
phases, etc., all with the view that the specifications and proposal 
signed by the successful bidder may become a contract which will 
work to the advantage and justice of both the Government and the 
contractor. 

Attention is especially directed to instructions for sampling given 
in the specifications which become a part of the contract. Prior to 
the fiscal year 1912-13 the method of sampling was given scant 
mention, leaving one of the most important features determining the 
successful and satisfactory application of the specification method 
of the purchase of coal almost wholly in the hands of the purchaser, 
the seller having little or no means whereby he could exercise a con¬ 
trol of the manner and method of collecting and preparing samples 
that should represent the coal furnished. It is as essential that an 
established and an agreed-upon method of sampling be followed, as 
it is that the sample be analyzed by a reputable laboratory; in fact, 
the samphng is of first consequence, for if a sample is haphazardly 
taken and carelessly reduced to a quantity convenient for trans¬ 
mittal to the laboratory, and hence is nonrepresentative, it is usually 
impossible or impracticable to get another sample; whereas if the 
analysis and test of a representative sample are in error, the remain¬ 
ing part of the sample can he analyzed and tested, by another labo¬ 
ratory if deshed. Unwarranted corrections in price and resulting 
injustice and hardship to the buyer or seller may easily and unin¬ 
tentionally occur through lack of perception of the relative impor¬ 
tance of sampling and the observance of proper methods of collecting 
and preparing samples. By clearly setting forth the method of 
sampling as a part of the contract, the seller or the buyer has some¬ 
thing tangible on which to base legitimate complaints if samples are 
not properly collected and prepared. Such is the purpose of putting 
in the Government specifications the method of sampling in some 
detail. 

As the specifications given herein are so general, applying generally 
to all coals purchased by the Government under every condition of 
delivery, it is impossible to state therein more specific directions for 
sampling, but for any particular conditions of delivery more definite 
directions can be prepared and proper consideration for the character 
of the coal given. By observance, however, of the general directions 
for sampling, which are given in the specifications that follow, samples 


42 


METHODS OF SAMPLING DELIVERED COAL. 


that are fairly representative of the coal sampled can be obtained 
without difficulty. 

Though a contract may be let under the specification basis, the 
sampling of small orders of, say, 50 tons or less, may be discretionary 
with the Government, a provision to this effect appearing in the 
contract. If samples are not taken the bid price per ton is paido 
This discretionary right of sampling small orders or tonnages makes 
it unnecessary to sample small deliveries under one large general 
contract of from a half to a few tons to small launches or boats, or to 
different quarters or buildings where facilities for sampling or storing 
accumulated samples are not at hand. It is obvious that the expense 
of collecting and preparing a sample to represent such small tonnages, 
together with the cost of analysis, would make the unit cost per ton 
ordinarily prohibitive and disadvantageous. 

Under ‘‘Price and Payment” for bituminous coal (p. 51), 2 per 
cent variation from the guaranteed standard of British thermal units 
(B. t. u.) is allowed before price corrections. On 14,000 B. t. u., 
“dry coal,” this means that there is no price correction for delivered 
coal of an apparent heating value as reported by the laboratory 
between 13,720 and 14,280. This is allowed to provide {a) for the 
reasonable variations that, it is recognized, may be obtained with the 
same 5-pound sample in two different determinations in the same 
laboratory, (Jb) for variations that result in preparing and reducing 
the gross sample to a quantity convenient for transmittal to the 
laboratory, (c) for variations due to the collection of gross samples 
as representing the coal sampled, and {d) for allowing the contractor 
latitude in the preparation of the coal, as it is recognized that the 
quality of his coal expressed in terms of ash and B. t. u. can not be 
controlled within strictly narrow limits. 

In interpreting a heating value determination, then, the value 
reported by the laboratory must be considered as the apparent value 
of the coal sampled, as the actual value of the coal may have been 
more or less than the apparent value because of the variations above 
cited. If the reported value differs by more than 2 per cent from the 
guaranteed standard, the result is considered as evidence that coahof 
a quality other than that contracted for was delivered and the price 
is corrected accordingly. If a number of gross samples are taken to 
represent a total quantity of coal delivered, and a report is obtained 
by averaging the several analyses and tests, the apparent value 
reported by the laboratory may be within 1 per cent or less of the 
actual value of the entire quantity, but in specifications as general as 
those given herein a 2 per cent variation from the standard is considered 
more equitable and wiU eliminate frequent and unwarranted price 
corrections, especially if payment for a delivery or order is based on 
a single determination. In the sampling of cargo shipments to the 


COAL SPECTFICATTONS AND PROPOSALS. 


43 


Isthmus of Panama (p. 19) the reported results between two separate 
and independent series of samples representing the same cargo agree 
on an average within less than 50 B. t. u. The samples are collected 
by experienced collectors and prepared very systematically, and the 
reported results for a cargo are determined by averaging a number of 
analyses. With such sampling the variations above enumerated are 
largely averaged and eliminated, and the variation that may be 
allowed before price corrections may, under such conditions, be 
reduced to 1 per cent or even less. 

It is not the intent of the specifications continually to make correc¬ 
tions in price for slight variations of the actual heating value from the 
guaranteed standard, and it is desired to eliminate corrections which 
are unwarranted because of the difference between the reported 
apparent heating value and the actual heating value, the first purpose 
of the specifications being to insure that the Government is receiving 
coal similar within reasonable limits to the standard of the contract. 

The power and heating plant specifications require the bidder to 
specify the quality of coal offered in terms of moisture, ^^as received,” 
ash, sulphur, volatile matter, and B. t. u., ‘^dry coal;” these values 
becoming the standards of the contract to determine rejectable coal 
and the price to be paid for delivered coal. Bidders have in some 
cases specified a higher B. t. u. value and a lower ash content than the 
quality of the coal warranted, upon the theory that the high B. t. u. 
and low ash values would give them an advantage in the comparison 
of bids. The bid price may be correspondingly higher, the bidder 
presumably expecting a deduction to be made and to receive a price 
on his delivered coal lower than the bid price. The apparent price 
may be, therefore, higher than the actual price received, and use may 
be made of the apparent price for advertising purposes. Bidders are 
cautioned against offering higher standards than can be maintained 
on an average, for to do so may result in the bid being rejected 
(see sec. 8, p. 47, of the specifications), or may result in excessive 
penalties, the purchase of coal in the open market, the difference in 
cost of coal so purchased being charged against the contractor, or 
may lead to the cancellation of the contract (see sec. 30, p. 50). 

By reference to the specifications for anthracite, broken, egg, stove, 
and chestnut sizes, it will be noted that bidders are not required 
to specify the quality of the coal in terms of ash, B. t. u., moisture, 
sulphur, and volatile matter, and that regular and systematic sam¬ 
pling of aU deliveries is not required to determine the price to be paid 
for each and every delivery. The specifications provide, however, 
for the sampling of coal that proves unsatisfactory because of exces¬ 
sive ash or clinkering and for price corrections if the ash as shown 
by analysis is in excess of a permitted variation from the standard 


44 


METHODS OF SAMPLING DELIVERED COAL. 


for the particular size of coal, these standards being determined from 
hundreds of ash determinations made during a period of six years. 
B. t. u. standards are not used, as it has been determined that the 
heating value for the different sizes is, in the main, a function of the 
ash content, varying inversely and in proportion with the ash; that 
is to say, if the ash content is increased, for example, 1 per cent, the 
heating value is decreased 1 per cent. 

Because of economic considerations and the physical character of 
anthracite, the specifications used for bituminous and the small sizes 
of anthracite coal requiring sampling are not adapted for the purchase 
of the large sizes of anthracite. Most of the Government contracts 
for these sizes are for relatively small yearly tonnages with deliveries 
of J ton to 50 tons, but seldom more to a building. To collect regu¬ 
larly samples from such small deliveries would make the unit cost per 
ton of sampling prohibitive, the cost being generally greater than any 
probable saving. To obtain samples that would fairly represent the 
quality of these coals would require collecting samples of 1,000 to 
1,500 pounds, or more, and to obtain a final sample for analysis that 
would represent the gross sample within reasonable limits would 
require crushing and recrushing the gross sample, thereby perhaps 
destroying the value of the gross sample for use in a house-heating 
furnace or stove, and largely wasting it, unless a Government steam- 
power plant were available in which it could be advantageously 
burned. The total or partial loss in value of 1,000 or 1,500 pounds 
of coal at $5 to $10 per ton from a small delivery is manifestly a matter 
deserving consideration. Owing to the hardness and brittleness of 
anthracite, the crushing of a gross sample by hand is difficult and 
tedious and requires hours of labor; in fact, a mechanical means of 
crushing is almost absolutely necessary, but the cost of the necessary 
equipment would prove prohibitive in the case of small contracts. 

Because of the above facts, as well as the manner in which anthra¬ 
cite is prepared at the colliery and the small area of the Pennsylvania 
anthracite fields, and because of other considerations, the Govern¬ 
ment does not consider the application of the specifications which 
are adapted for bituminous coal generally suitable for the purchase 
of the large sizes of anthracite. The specifications that are used 
provide for the acceptance and use of coal and payment at contract 
price so long as no difficulty is experienced, and the collection of 
samples is necessary only as set forth in the specifications. 

Anthracite is graded into sizes before shipment, and each grade 
commands a certain price. The size of the openings in screens and 
the types of screens used in preparing the sizes may vary slightly; 
however, the following table indicates the commercial sizes of 
anthracite: 


COAL SPECIFICATIONS AND PROPOSALS. 


45 


Sizes of anthracite. 


Sizes. 


Prepared with square- 
mesh screens. 


Through 
meshes 
having 
opening 
of—' 


Over 

meshes 

having 

opening 

of— 


Prepared with round- 
mesh screens. 


Through 

meshes 

having 

diameter 

of— 


Over 

meshes 

having 

diameter 

of— 


Broken (furnace). 

Egg. 


Inches. 


Inches. 


4 

2| 


25 

2 


Inches. 

3i 


Inches. 


3J 

2i 


Stove. 

Nut (chestnut). 

Pea. 

Buckwheat No.l. 

Buckwheat No. 2, or rice... 
Buckwheat No. 3, or barley 


2 

If 


a 

4 


If 

A 

4 


i 






2i 

U 

i 

ft 

A 


li 

i 


a- a- a- 


















SPECIFICATIONS AND PROPOSALS FOR BITUMINOUS 
AND ANTHRACITE COAL. 


(Office issuing the proposals.) 


(Place.) 


(Date.) 

I. PROPOSALS. 


Date to be de- 1. Sealed proposals, in duplicate, on blank forms supplied by the 

., to furnish such quantities of coal as specified 

herein as may be required for use of the., for the 

fiscal year ending June 30, 191.., will be received until 2 o’clock p. m., 
., at the office of the., and 


Bidder may be 
present. 

Address of pro¬ 
posals. 


Form and signa¬ 
ture. 


Cash or certi¬ 
fied check. 


then opened. 

2. Each bidder shall have the right to be present, either in person 
or by attorney, when the bids are opened. 

3. Proposals, in duplicate, must be forwarded to the. 

., postage prepaid. Addressed envelope for mailing 

is inclosed herewith. 

4. Proposals must be made in duplicate on the form given herein, 
and must be signed by the individual, partnership, or corporation 
making the same; when made by a partnership,the name of each 
partner must be signed. If made by a corporation, proposals must be 
signed by the officer thereof authorized to bind it by contract, and be 
accompanied by a copy, under seal, of his authority to sign. 

5. The proposals must be accompanied by cash or by certified check 

drawn payable to the order of the., in the amount 

equal to 2 per cent of the estimated amount involved for the fuel for 
which bids are submitted, the minimum amount in any case to be $10. 
This requirement is solely to guarantee, if the award is made on the 
proposal, that within 10 days after notice is given that an award has 
been made, the bidder will enter into a contract in accordance with 
the terms of the proposal and execute a bond for the faithful perform¬ 
ance thereof, with good and sufficient sureties as hereinafter required. 
In the event of the failure of the bidder to enter into contract or execute 
bond, the cash or check guaranty will be forfeited. 


II. CONTRACTOR’S BOND. 

Sureties. G. Each contractor shall be required to give a bond, with two or more 

individual sureties or one corporate surety duly qualified under the 
act of Congress approved August 13, 1894, in which the contractor and 
the sureties shall covenant and agree that, in case the said contractor 
shall fail to do or perform any or all of the covenants, stipulations, and 
agreements of said contract on the part of the said contractor to be per¬ 
formed as therein set forth, the said contractor and his sureties shall 
forfeit and pay to the United States of America any and all damages 
sustained by the United States by reason of any failure of the contractor 
fully and faithfully to keep and perform the terms and conditions of 
46 












SPECIFICATIONS AND PKOPOSALS FOR COAL. 


47 


his contract, to be recovered in an action at law in the name of the 
United States in any proper court of competent jurisdiction. Such 
sureties (except corporate sureties) shall justify their responsibility by 
affidavit showing that they severally own and possess property of the 
clear value in the aggregate of double the amount of the above-men¬ 
tioned forfeiture over and above all debts and liabilities and all prop¬ 
erty by law exempt from execution; the affidavit shall be sworn to 
before a judge or a clerk of a court of record or a United States attorney, 
who must certify of his own personal knowledge that the sureties are 
sufficient to pay the full penalty of the bond. 

7. If the estimated amount involved in the contract does not exceed May be waived, 
the sum of $200, then the bond may be waived with the consent of the 
department involved. 


III. RESERVATIONS. 


8. The right is reserved by the Government to reject any and all bids _R e j e c t i o n of 
and to waive technical defects. Bidders are cautioned against guar¬ 
anteeing higher standards of quality than can be maintained in deliv¬ 
ered coal (this applies especially to bituminous coal and the steam 

sizes of anthracite), as the Government reserves the right to reject any 
and all bids, if the Government has information regarding analyses and 
test results that indicate that higher standards have been offered than 
probably can be maintained. 

9. The right shall be reserved by the Government to purchase for Tests, 
the purpose of making boiler tests other coal than that herein con¬ 
tracted for, provided the amount so purchased shall not exceed 10 per 

cent of the estimated consumption during the period covered by this 
agreement. 

10. If it should appear to be to the best interests of the Government Lowest bids 
to do so, the right is reserved to award the contract for supplying coal 

at a price higher than that named in a lower bid, or in lower bids. 

11. If the bidder to whom the award is made shall fail to enter into Failure to con- 
a contract as herein provided, then the award may be annulled and 

the contract let to the next most desirable bidder without further 
advertisement, and such bidder shall be required to fulfill every stipu¬ 
lation expressed herein, as if he were the original party to whom the 
contract was awarded; provided, however, that such bidder is notified 
of said award within 60 days after the date on which the bids on this 
contract were opened. If such notice should not be given within said 
60 days, then the acceptance of the award will be optional with the 
said bidder. 

12. No contract can be lawfully transferred or assigned. Contracts non- 

** ^ t/i'9,risf6r&bl0 

13. No proposal will be considered from any person, firm, or corpora- Default, 
tion in default of the performance of any contract or agreement made 

with the United States, or conclusively shown to have failed to 
perform satisfactorily such contract or agreement. 


IV. QUANTITY. 


14. The estimated quantity of coal in . tons of 2,000 

pounds to be purchased is based upon the previous annual consump¬ 
tion, but the right will be reserved to order a greater or less quantity, 
subject to the actual requirements of the service. 



48 


METHODS OF SAMPLING DELIVERED COAL. 


V. DELIVERY. 


Quantity, time, 
and place. 

Rapidity. 


Failure to de¬ 
liver. 


Hours. 


Weighing. 


15. The coal shall be delivered in such quantities at such times as 
the Government may direct. (Place of delivery to be stated.) 

16. All the available storage capacity of the Government coal bunkers 
shall be placed at the disposal of the contractor to facilitate delivery 
of coal under favorable conditions. When an order is issued for coal, 
the contractor upon commencing a delivery on that order shall continue 
the delivery with such rapidity as not to waste unduly the services of 
the Government inspector. 

17. After verbal or written notice shall have been given to deliver coal 
under this contract a second notice may be served in writing upon the 
contractor to make delivery of the coal so ordered within a reasonable 
time, to be determined by the Government official in charge, after 
receipt of said second notice. Should the contractor for any reason fail 
to comply vdth the second request, the Government shall be at liberty 
to buy coal independent of this contract, and for coal so purchased to 
charge against the contractor and his sureties any excess in price over 
the price which would have been paid to the contractor had the coal 
been delivered by him. 

18. The contractor shall be allowed to deliver coal d\iring the usual 
hours of teaming—that is, between 8 a. m. and 5 p. m. 

19. (To be stated by whom and where the coal shall be weighed, etc.) 


VI. SAMPLING. 

Contractor 20. The contractor shall have the privilege of having a representa- 
present.^^ tive present to witness the collection and preparation of the samples to 
be forwarded to the laboratory’-. 

Method. 21. The samples shall be collected and prepared in accordance with 

the method given in Appendix A, attached hereto as a part of these 
specifications and proposals. 


VII. ANALYSES. 

Laboratory and 22. The samples shall be immediately forwarded to the Bureau of 
Mines, Department of the Interior, Washington, D. C., and they shall 
be analyzed and tested in accordance with the method recommended 
by the American Chemical Society and by the use of a bomb calo¬ 
rimeter. Such analyses and tests shall be made at no cost to the con¬ 
tractor. The results shall be reported by the Bureau of Mines in not 
more than fifteen (15) days after the receipt of the sample. If more 
than one sample is received from the same delivery, the fifteen (15) 
days shall date from the receipt of the last sample taken. 


VIII. BITUMINOUS AND ANTHRACITE PEA AND BUCK¬ 
WHEAT COAL FOR POWER AND HEATING PLANTS. 


DESCRIPTION OF COAL DESIRED. 

must be a good coal. 

(kind and size to be specified), and must be adapted for successful use 
in the particular furnace and boiler equipment. 
be^°su^lied^ by required to specify the coal offered in terms of 

bidder. moisture in the coal “as received, ” and of ash, volatile matter, sulphur, 



SPECIFICATIONS AND PROPOSALS FOR COAL. 


49 


and British, thermal units in “dry coal,” such values to become the 
standards for the coal of the successful bidder. In addition, the bidders 
are required to give the trade name of the coal offered, the name or 
other designation of coal bed, name of mine or mines, location of mine 
or mines (town, county, and State), railroad on which mine or mines 
are located, and name of operator of mine or mines. This information 
shall be furnished in spaces provided hereinafter. 

Note. —Bids not supplying the foregoing information may be con¬ 
sidered informal and rejected. 

Coal of the description and analysis specified is herein known as coal 
of the contract grade. Bidders are cautioned against specifying higher 
standards than can be maintained, for to do so will result in deductions 
in price and may result in the rejection of dehvered coal or the cancel¬ 
lation of the contract. In this connection it should be recognized that 
the small “mine samples” usually indicate a coal of higher economic 
value than that actually delivered in carload lots, because of the care 
taken to separate extraneous matter from the coal in the “mine 
samples.” 

AWARD. 

25. In determining the award of this contract consideration will be Considerations, 
given to the quahty of the coal (expressed in terms of moisture in coal 

“as received,” of ash in “dry coal,” and British thermal units in “dry 
coal”) offered by the respective bidders and to the operating results 
obtained with the same and with similar coals on previous contracts or 
by test, as well as to the price per ton. 

26. Bids may be rejected from further consideration if they offer Bids subject to 
coals regarding which the Government has information that they 

possess unsatisfactory physical characteristics or volatile matter or 
sulphur or ash contents, or that they are unsatisfactory because of 
clinkering or excessive refuse, or because of having failed to meet the 
requirements of city smoke ordinances, or for other cause that would 
indicate that they are of a character or quahty that the Government 
considers unsuited for the storage space or the furnace equipment of the 
particular contract. 

27. In order to compare bids as to the quahty of the coal offered, all Method of com- 
proposals shall be adjusted to a common basis. The method used shall bids. 

be to merge the four variables—moisture content, ash content, heating 
value, and price bid per ton—^into one figure, the cost of 1,000,000 
British thermal units. The procedure under this method shall be as 
foUows: 

(а) All bids shall be reduced to a common basis with respect to 
moisture, by dividing the price quoted in each bid by the difference 
between 100 per cent and the percentage of moisture guaranteed in the 
bid. The adjusted bids shall be figured to the nearest tenth of a cent. 

(б) The bids shall be adjusted to the same ash percentage by selecting 
as the standard the proposal that offers coal containing the lowest 
percentage of ash. The difference in ash content between any given 
bid and this standard shall be divided by 2 and the price in such bid, 
adjusted in accordance with the above, multiplied by the quotient. 

The result shall be added to the above adjusted price. The adjusted 
bids shall be figured to the nearest tenth of a cent. 


50 


METHODS OF SAMPLING DELIVERED COAL. 


(c) On the basis of the adjusted price, allowance shall then be made 
for the varying heat values by computing the cost of 1,000,000 British 
thermal units for each coal offered. This determination shall be made 
by multiplying the price per ton adjusted for ash and moisture contents 
by 1 , 000 , 000 , and dividing the result by the product of 2,000 multiplied 
by the number of British thermal units guaranteed. If the coal is pur¬ 
chased on the basis of 2,240 pounds to the ton, the factor of 2,240 
should be used instead of 2 , 000 . 

Service test. 28. After the elimination of undesirable bids, the selection of the 
lowest bid of those remaining on the basis of the cost per 1 , 000,000 
British thermal units may be considered by the Government as a 
tentative award only, the Government reserving the right to have 
practical service test or tests made under the direction of the Bureau 
of Mines, the results to determine the final award of contract. The 
interested bidder or his authorized representative may be present at 
such test. 

CAUSES FOR REJECTION. 

Coal subject to 29. It is understood that coal containing 3 per cent more moisture, 
rejection. ^ qj. 3 pgr gent more volatile matter, or 1 per cent 

more sulphur, or 4 per cent fewer British thermal units than the speci¬ 
fied guaranties as to the standards for the coal hereunder contracted 
for, or coal furnished from a mine or from mines other than herein 
specified by the contractor, unless upon written permission of the 
Government, shall be considered subject to rejection, and the Govern¬ 
ment may, at its option, either accept or reject the same. Should the 
Government have consumed a part of such coal subject to rejection, 
such consumption shall not impair the Government’s right to cause 
the contractor to remove the remainder of the delivered coal subject 
to rejection. 

Cancellation of 30. It is agreed that if the contractor shall furnish coal in three 
market^rchases ^consecutive deliveries, or in case more than 20 per cent of the coal 
delivered to any date during the life of this contract shall contain 3 
per cent more moisture, or 2 per cent more ash, or 3 per cent more 
volatile matter, or 1 per cent more sulphur, or 2 per cent fewer British 
thermal units than the specified guaranties as to the standards for the 
coal hereunder contracted for, or if coal is furnished from a mine or 
from mines other than herein specified, unless upon the written per¬ 
mission of the Government, then this contract may, at the option of 
the Government, be terminated, or the Government may, at its option, 
purchase coal in the open market until it may become satisfied that 
the contractor can furnish coal equal to the standards guaranteed, and 
the Government shall have the right to charge against the contractor 
any excess in price of coal so purchased over the corrected price that 
would have been paid to the contractor had the coal been delivered 
by him. 

Removal of re- 31. The contractor shall be required to remove, without cost to the 
jectedcoal. Government, within 48 hours after notification, coal that has been 
rejected by the Government. Should the contractor not remove 
rejected coal within the said 48 hours, the Government shall then be 
at liberty to have the said coal removed from its premises and to dis¬ 
pose of such coal by sale, as the Government shall elect. The proceeds 
from such sale, less all costs incidental to its removal and to the sale, 
shall be paid over to the contractor. 


SPECIFICATIONS AND PROPOSALS FOR COAL. 


51 


PRICE AND PAYMENT. 


32. The Government hereby agrees to pay the contractor within Determination 
thirty (30) days after the completion of an order or delivery for each 
ton of 2,000 pounds of coal delivered and accepted in accordance with 
all the terms of this contract, the price per ton determined by taking 
the analysis of the sample, or the average of the analyses of the samples 
if more than one sample is analyzed, collected from the coal delivered 
upon the basis of the price herein named, adjusted as follows for varia¬ 
tions in heating value, ash content, and moisture content from the 
standards guaranteed herein by the contractor. (See paragraph 13 in 
appendix for exception to this method:) 

(a) Considering the coal on a “dry-coal” basis, no adjustment in Heat unit ad- 
price shall be made for variations of 2 per cent or less in the number 
of British thermal units from the guaranteed standard. When the 
variation in heat units exceeds 2 per cent of the guaranteed standard, 
the adjustment shall be proportional and shall be determined by the 
following formula: 

B. t. u. delivered coal (“dry-coal” basis) * 

B. t. u. (“dry-coal” basis) specified in contract><^^^ price=price re¬ 
sulting for B. t. u. variation from the standard. 

The adjusted price shall be figured to the nearest tenth of a cent. 

As an example, for coal delivered on a contract guaranteeing 14,000 
British thermal units on a “dry-coal ” basis at a bid price of $3 per ton, 
showing by calorific test results varying between 13,720 and 14,280 
British thermal units, there would be no price adjustment. If, how¬ 
ever, by way of further example the delivered coal shows by calorific 
test 14,350 British thermal units on a “dry-coal” basis, the price for 
this variation from the contract guaranty would be, by substitution 
in the formula: 


14,350 

14,000 


XI3=$3.075 


(6) No adjustment in price shall be made for variations of 2 per adjust¬ 

or less below or above the guaranteed percentage of ash on the “dry- 
coal” basis. When the variation exceeds 2 per cent, the adjustment 
in price shall be determined as follows: 

The difference between the ash content by analysis and the ash 
content guaranteed shall be divided by 2 and the quotient shall be 
multiplied by the bid price, and the result shall be added to or de¬ 
ducted from the B. t. u. adjusted price or the bid price, if there is no 
B. t. u. adjustment, according to whether the ash content by analysis 
is below or above the percentage guaranteed. The adjustment for 
ash content shall be figured to the nearest tenth of a cent. 

As an example of the method of determining the adjustment in cents 
per ton for coal containing an ash content varying by more than 2 per 
cent from the standard, consider that coal for which the above-men¬ 
tioned heat unit adjustment is to be made has been delivered on a 
contract guaranteeing 10 per cent ash, and shows by analysis an ash 
content of 7.50 per cent. The adjustment in price would be deter¬ 
mined as follows: 

The difference between 10 and 7.50, which is 2.50, would be divided 
by 2, and the quotient of 1.25 multiplied by $3, resulting in an adjust- 




52 


METHODS OF SAMPLING DELIVERED COAL. 


ment of 3.7 cents per ton, which in this case would be an addition. 
The price after adjustment for the variations in heating value and ash 


Moisture a d - 
justment. 


Partial 

ment. 


p ay - 


content would be $3,075 plus $0,037, or $3,112. 

(c) The price shall be further adjusted for moisture content in excess 
of the amount guaranteed by the contractor, the deduction being de¬ 
termined by multiplying the price bid by the percentage of moisture 
in excess of the amount guaranteed. The deduction shall be figured 
to the nearest tenth of a cent. 

As an example, consider that coal for which the above-mentioned 
heat unit and ash adjustments are to be made, and as having been de¬ 
livered on a contract guaranteeing 3 per cent moisture, and that the 
coal shows by analysis 4.50 per cent moisture; then the bid price 
would be multiplied by 1.50 (representing excess moisture), giving 
4.5 cents as the deduction per ton. The price to be paid per ton for 
the coal would then be $3,112, less $0,045, or $3,067. 

33. If coal on visual inspection by the Government inspector appears 
to be acceptable coal, the Government shall have the right, immediately 
on the completion of an order, to make payment on 90 per cent of the 
amount of the bill, based on the tonnage delivered and the bid price 
per ton. The 10 per cent withheld is to cover any deduction on account 
of the delivery of coal that on analysis and test is subject to an adjust¬ 
ment in price. If the 10 per cent withheld should not be sufficient to 
cover the deduction, then the amount due the Government may be 
taken from any money thereafter to become due to the contractor, or 
may be collected from the sureties. Because of the distance of the 
point of delivery from the laboratory, requiring several days for the 
transmittal of samples and the return of analytical report, because of 
loss of the original sample, necessitating the forwarding of the reserve 
sample, or for any other reason that would result in delayed payment, 
should such be withheld until receipt of analytical report, the Govern¬ 
ment may, as circumstances in its opinion warrant, exercise the fore¬ 
going right. 


IX. ANTHRACITE COAL—DOMESTIC SIZES. 

DESCRIPTION OF COAL DESIRED. 

Character and 34. The coal must be best quality, fresh-mined, anthracite, and it 
quality. must be well screened, practically free from dirt, must not contain 

undue percentages of moisture, slate, or bone, or of coal of smaller 
sizes, and must equal in quality and preparation the best anthracite 
coal produced. 

be^^.su^ifed^ by bidder shall be required to give the trade name of the coal 

bidder. ^ offered, the name or other designation of coal bed or beds, the name of 

mine or mines producing the coal, location of mine or mines (town, 
county, and State), the name and address of the operator of mine or 
mines, and the railroad upon which the mine or mines are located, 
this information to be given in spaces provided hereinafter. 

AWARD. 

Considerations. 36. In determining the award of the contract, consideration shall be 
given to the results obtained with coals furnished on previous Govern¬ 
ment contracts by the respective bidders, as well as to the price per ton. 


SPECIFICATION'S AND PROPOSALS FOR COAL. 


53 


CAUSES FOR REJECTION. 

37. If the percentage of bone, dirt, slate, or smaller sizes in a delivery Unsatisfactory 
exceeds the percentage required by the best preparation, or if the®°^^- 

given coal fails to give satisfactory results because of excessive clinker- 
ing or excessive ash-pit refuse, it shall be subject to rejection, and pay¬ 
ment may not be made for the remaining coal, and the Government 
shall have the right to cause the contractor to remove such coal at no 
cost to the Government. The Government may then purchase coal 
in the open market and make charge against the contractor for the 
excess in cost of coal so purchased. 

38. If it is impracticable for the Government to cause the contractor Ash deductions, 
to remove coal that produces excessive ash-pit refuse, samples may be 

taken during the consumption of such coal, provided not more than 50 
per cent of the delivery had been consumed, and if on analysis the ash 
content on the ‘‘dry-coal ” basis is equal to or greater than the following 
percentages for the respective sizes of coal, ten (10) per cent of the price 
of the delivery in question shall be deducted from any money due or 
that may thereafter be due the contractor: * 

Ash in 

Size of coal. “dry coal," 

per cent. 

Furnace. 14 

Egg. 15 

Stove. 16 

Chestnut. 18 

39. The Government inspector will not accept coal if, in his opinion. Unacceptable 
on visual inspection, it is subject to rejection, or if it contains an undue 

♦percentage of moisture, and he shall have the right to refuse to accept 
coal from a source other than that specified by the bidder, unless the 
contractor shall have received permission from the Government to 
substitute said coal. 

40. If the contractor furnishes coal in three consecutive deliveries, or Cancellation of 
in case 20 per cent of the amount of the coal delivered to any date during 

the life of the contract is, in the opinion of the Government, subject to 
rejection, then the contract may, at the option of the Government, be 
terminated by written notice to the contractor to that effect. 

PRICE AND PAYMENT. 

41. Payment shall be made within thirty (30) days after the com¬ 
pletion of an order and shall be based on the contract price, provided 
the coal is not subject to rejection. 

X. INFORMATION TO BE SUPPLIED BY BIDDERS. 

42. The following spaces should be filled in by the bidder for each bid, 
for if the information called for is not supplied, the proposal may be 
regarded as informal. 

(Bidders are cautioned against specifying higher standards than can 
be maintained, for to do so may result in the bid being rejected, or may 
result in rejection of delivered coal or cancellation of the contract and 
the Government purchasing coal in the open market and charging 
against the contractor the difference in cost. See paragraphs 8, 29, 

30, 31.) 


(To be signed by office issuing proposals. 








54 


METHODS OF SAMPLING DELIVERED COAL. 


The undersigned agree.. to furnish to the.. 

the coal described below, in tons of 2,000 pounds each, and in quantity 
as may be required during the fiscal year ending June 30, 191.., in 
accordance with the foregoing specifications; the coal to be delivered 
in such quantities and at such times as the Government may direct. 

(а) Kind and size of coal. 

(б) Commercial name of coal. 

(c) Name of mine or mines. 

(d) Location of mine or mines (town, county, and State). 


(e) Name or other designation of coal bed or beds 


(/) Railroad on which mine or mines are located 


(g) Name of operator of mine or mines. 

(h) Percentage of moisture in coal “as received”. 

(i) Percentage of ash in ‘ ‘ dry coal ”. 

(j) Percentage of volatile matter in “dry coal ”. 

(k) Percentage of sulphur in “dry coal”. 

(l) British thermal units per pound of “dry coal ”. 

(m) Additional description of coal deemed of importance by the 

bidder.. 


(n) Price per ton of 2,000 pounds for delivery (for bituminous coal 
and for pea and buckwheat sizes of anthracite this price is understood 
to be the bid price per ton, see paragraph 32 for method of determining 
price for delivered coal). . 

Note.—^T he information called for under h, i,j, k, and I is not required for bids on 
the domestic sizes of anthracite coal; that is, furnace, egg, stove, and chestnut. 

The undersigned ha., read the specifications and proposals and 
agree.. to comply therewith in every particular. 


Signature of each member of the firm and firm name. 
If a corporation, its name and signature of the officer au¬ 
thorized to sign for the corporation, together with acopy, 
under seal of his authority, to sign; also the name of the 
State in which incorporated. 


Doing business under the firm name of. 

Place of business. 

Date. 

Note.—O wing to the difficulty in deciphering signatures, a typewritten copy of 
same should be attached. 




























APPENDIX A. 

METHOD OF SAMPLING COAL DELIVERIES. 


(To be attached to and to become a part of the Specifications and 

Proposals issued by the Ofiice of the ., for the 

purchase of coal for the fiscal year commencing July 1, 191.., and 
ending June 30, 191...) 

Note.—A s payment for bituminous and the steam sizes of anthracite coal is to be 
based upon the quality as shown by analyses of representative samples, it is imperative 
that every sample be collected and prepared carefully and conscientiously and in strict 
accordance with the method agreed upon herein, for if the sampling is improperly done, 
a determined price based on the analysis will be in error and it may be impossible or 
impracticable to take another sample: but if an analysis is in error, another analysis 
can easily be made of the original sample. 

Gross samples of the quantities designated herein must be taken whether the delivery 
consists of a few tons or several hundred tons, because of the following cardinal principle 
in sampling coal that must be recognized and understood; that is, the effect of the 
chance inclusion or exclusion of too many or too few pieces of slate, or other impurities 
in what, or from what, would otherwise have been a representative sample will cause 
the analysis to be in error accordingly, regardless of the tonnage sampled. For example, 
the chance inclusion or exclusion of 10 pounds too much or too little of impurities in or 
from an otherwise representative sample of 100 pounds would cause the analysis to show 
an error in ash content and heatiug value of approximately 10 per cent, whereas for a 
1,000-pound sample, the effect would be approximately only 1 per cent, the effect being 
the same whether the sample is collected from a 1-ton lot or from a lot consistiug of several 
hundred tons. 

1. The coal shall be sampled when it is being loaded into or Time of sam 
unloaded from railroad cars, ships, barges, or wagons, or when dis-^^^^* 
charged from supply bins, or from industrial railway cars, or grab 

buckets, or from the coal-conveying equipment, as the case may be 
and as may be mutually agreed upon. If the coal is crushed as received, 
samples usually can be taken advantageously after the coal has passed 
through the crusher. Samples collected from the surface of coal in 
piles or bins, or in cars, ships, or barges, are generally unreliable. 

2. To collect samples, a shovel or specially designed tool or size of Incre- 
mechanical means shall be used for taking equal portions or incre-“®“^^* 
ments. For slack or small sizes of anthracite, increments as small as 

5 to 10 pounds may be taken, but for run-of-mine or lump coal the 
increments should be at least 10 to 30 pounds. 

3. The increments shall be regularly and systematically collected, Collection of 
so that the entire quantity of coal sampled will be represented pro- sample, 
portiona’tely in the gross sample, and with such frequency that a gross 

sample of the required amount shall be collected. The standard gross 
sample shall not be less than 1,000 pounds, except that for slack coal 
and small sizes of anthracite in which the impurities do not exist in 
abnormal quantities or in pieces larger than f inch, a gross sample of 
approximately 500 pounds shall be considered sufficient. If the coal 
contains an unusual amount of impurities, such as slate, and if the 
pieces of such impurities are very large, a gross sample of 1,500 pounds 
or more shall be collected. The gross sample should contain the same 
proportion of lump coal, fine coal, and impurities as is contained in 

55 



56 


METHODS OF SAMPLING DELIVERED GOAL, 


the coal sampled. When coal is extremely lumpy it is best to break a 
proportional amount of the lumps before taking the various increments 
of a sample. Provision should be made for the preservation of the 
integrity of the sample. 

Quantity repre- 4 . A gross sample shall be taken for each 500 tons or less, or in case 
of larger tonnages for such quantities as may be agreed upon. 

Preparation. 5. After the gross sample has been collected, it shall be systematically 
crushed, mixed, and reduced in quantity to convenient size for trans¬ 
mittal to the laboratory. The sample may be crushed by hand or by 
any mechanical means, but under such conditions as shall prevent loss 
or the accidental admixture of foreign matter. Samples of the quan¬ 
tities indicated in Table 1 following shall be so crushed that no pieces 
of coal and impurities will be not greater in any dimension, as judged 
by the eye, than specified for the sample before division into two ap¬ 
proximately equal parts. 


Table 1.— Largest sizes of coal and impurities allowable in samples 
ranging from 1,000 to 30 pounds in weight. 


Weight of sample Largest size of coal and impurities 

to be divided, allowable in sample before 

pounds. division. 

1,000 or more . 1 inch. 

500 . i inch. 

250 . i inch. 

125. finch. 

60. i inch. 

30.re inch, or 4-mesh screen. 


tion. 


The method of reducing by hand the quantity of coal in a gross 
sample shall be carried out as prescribed below, even should the ini¬ 
tial size of the coal and impurities be less than Table 1. 

Hand prepara- 6 . The progressive reduction in the weight of the sample to the quan¬ 
tities indicated in Table 1 shall be done by the follo^ving methods, 
which are shown in the^accompanying illustration (PL V); 

Mixing and re- (a) The alternate-shovel method of reducing the gross sample shall 
cartog altenSe repeated until the sample is reduced to approximately 250 pounds; 
shovelfuls. and care shall be observed before each reduction in quantity that the 
sample has been crushed to the fineness prescribed in Table 1. 

The crushed coal shall be shoveled into a conical pile (figs. 2 and 7) 
by depositing each shovelful of coal on top of the preceding one, and 
then formed into a long pile in the following manner: 

The sampler shall take a shovelful of coal from the conical pile and 
spread it out in a straight line (figs. 3, A, and 8 , A) having a width equal 
to the width of the shovel and a length of 5 to 10 feet. His next shovel¬ 
ful shall be spread directly over the top of the first shovelful, but in the 
opposite direction, and so on back and forth, the pile being occasion¬ 
ally flattened until all the coal has been formed into one long pile (figs. 
8 , B, and 8 , B). The sampler shall then discard half of this pile, pro¬ 
ceeding as follows: 

Beginning on one side of the pile, at either end, and shoveling from 
the bottom of the pile, the sampler shall take one shovelful (shovelful 
No. 1 , figs. 4 and 9) and set it aside; advancing along the side of the 
pile a distance equal to the width of the shovel, he shall take a second 
shoveful (shovelful No. 2, figs. 4 and 9) and discard it; again advancing 








BULLETIN 116 PLATE V 


First stage in the 
preparation of 
1,000 -pound 
sample. 


Second stage. 


Third stage. 


Fourth stage. 


Fifth stage. 


Sixth stage. 


BUREAU OF MINES 


-- ___ _ 



. .5 

Crush 1,000-po 
hard, clean suri 

ded into two parts; 
rve; 5—reject 







- ---=^ 

10 

Crush 500-p 
(fig. 5, A) 

ded into two parts; 
rve; 5 —reject 


— 




15 

Crush 250-p 

(fig.io, ^)t 

ded into quarters 


NOTE 

SELECT A HARD, CLEAN 
SURFACE, FREE OF CRACKS 
AND PROTECTED FROM 
RAIN, SNOW, WIND, AND 
BEATING SUN. DO NOT LET 
CINDERS, SAND, CHIRPINGS 
FROM FLOOR, OR ANY 
OTHER FOREIGN MATTER 
GET INTO THE SAMPLE. 
PROTECT SAMPLE FROM 
LOSS OR GAIN IN MOISTURE 



Reject quarters B, B 





































































































































^ I 


* 9 '\ 

} 

f 

( f 



I 


1 . 


V 




p ■ •■ 

■* o 



- f 

» 


A' 

r 




« 


j 

c 


•t 


•4 




0 . 

r 



« 



' I 



.T 



* 


i*>. 











SPECIFICATIONS AND PROPOSALS FOR COAL. 


57 


in the same direction one shovel width, he shall take a third shovelful 
(shovelful No. 3, figs. 4 and 9) and add it to the first. Shovelful No. 

4 (figs. 4 and 9) is to be taken in a like manner and discarded, the fifth 
shovelful (No. 5, figs. 4 and 9) retained, and so on, the sampler advanc¬ 
ing always in the same direction around the pile, so that its size will be 
gradually reduced in a uniform manner. When the pile is removed, 
about half of the original quantity of coal should be contained in the 
new pile formed by the alternate shovelfuls which have been retained 
(figs. 5, A, and 10, A, show the retained halves, and 5, B, and 10, B, 
the rejected halves). 

(b) After the gross sample has been reduced by the above method to Mixing and re- 
appro ximately 250 pounds, further reduction in quantity shall be by ter^g.^ 
the quartering method. Before each quartering, the sample shall be 
crushed to the fineness prescribed in Table 1. 

Quantities of 125 to 250 pounds shall be thoroughly mixed by coning 
and reconing (figs. 12 and 13); quantities less than 125 pounds shall be 
placed on a suitable cloth, measuring about 6 by 8 feet, mixed by rais¬ 
ing first one end of the cloth and then the other (figs. 18, 24, and 30), so 
as to roll the coal back and forth, and after being thoroughly mixed 
shall be formed into a conical pile by gathering together the four corners 
of the cloth (figs. 19, 25, and 31). The quartering of the conical pile 
shall be done as follows: 

The cone shall be flattened, its apex being pressed vertically down 
with a shovel or board, so that after the pile has been quartered each 
quarter will contain the material originally in it. The flattened mass, 
which shall be of uniform thickness and diameter, shall then be marked 
into quarters (figs. 14, 20, 26, and 32) by two lines that intersect at right 
angles directly under a point corresponding to the apex of the original 
cone. The diagonally opposite quarters (B, B in figs. 16, 22, 28, and 
34) shall then be shoveled away and discarded and the space that they 
occupied brushed clean. The coal remaining shall be successively 
crushed, mixed, coned, and quartered until two opposite quarters shall 
equal approximately 10 pounds of ^-inch or 4-mesh size. This 10-pound 
quantity shall be divided into two equal parts and each part shall be 
placed in a container suitable for transportation and shall bear an un¬ 
broken seal. One of the samples shall be forwarded by the officer in 
charge to the Bureau of Mines, Department of the Interior, for analysis, 
and the other shall be held in reserve by the officer in charge. Should 
the sample forwarded be lost or damaged in transit, then the reserve 
sample shall be forwarded. 

7. Only such mechanical means as will give equally representative Mechanical 
samples shall be used in substitution for the hand method of prepara- 

tion herein specified. 

8 . For convenience, or if the accumulation of a sample would extend 
over any considerable period of time, the several quantities that would 
otherwise be combined to make up the gross sample may be worked 
down as collected and reduced to samples of a size suitable for trans¬ 
mittal to the laboratory, and these fractional samples may be analyzed 
and the several analyses averaged, or the several samples may later be 
mixed at the place of sampling or in the laboratory and reduced to one 
sample, one analysis being made. In the averaging of analyses or in 
the mixing of the several samples, weights shall be used proportionate 
to the tonnages which the fractional samples represent. 


58 


METHODS OF SAMPLING DELIVERED COAL. 


Special mois¬ 
ture sample. 


Collection of 
moisture sample. 


Moisture sam¬ 
ples discretion¬ 
ary. 


Moisture sam¬ 
ple may repre¬ 
sent any part of 
delivery. 


Sampling of 50 
tons or less dis¬ 
cretionary. 


9. In the reduction of the gross sample to the sample for trans¬ 
mittal to the laboratory, the gross sample may unavoidably lose mois¬ 
ture. To determine the moisture content in the coal delivered, a sepa¬ 
rate special moisture sample may be taken. This special moisture 
sample shall be taken so as to represent the coal with respect to the 
moisture contained at the time of weighing. 

10. The special moisture sample shall weigh approximately 100 
pounds, and shall be accumulated by placing in a waterproof receptacle 
with a tight-fitting and waterproof lid small equal parts of the freshly 
taken increments of the gross sample, or they may be collected sepa¬ 
rately and independently of the gross sample. The accumulated 
moisture sample shall be rapidly crushed and reduced mechanically 
or by hand to about a 5-pound quantity, which shall be immediately 
placed in a container and sealed air-tight and forwarded to the labora¬ 
tory. If prepared by hand, it shall be rapidly crushed so that no 
pieces of coal or impurities are larger than one-half inch, and it shall 
be rapidly reduced by the quartering method on a cloth to the 
5-pound quantity. 

11. The collection of special moisture samples shall be discretionary 
with the Government. If special moisture samples are not taken, the 
moisture determined for the gross sample shall govern, provided the 
gross sample shall be taken so as to represent the coal with respect to 
the moisture contained at the time of weighing, otherwise the moisture 
determination shall be waived. 

12 . A special moisture sample may be taken from any one railroad 
car or cars, or from a part of a delivery, if, in the opinion of the Govern¬ 
ment, said car or cars, or said part of a delivery contains moisture in 
excess of the amount guaranteed by the contractor, and should the mois¬ 
ture content of this special sample be in excess of the moisture content 
guaranteed by the contractor, then the Government shall have the 
right to make a deduction in price in accordance with paragraph 32 (c) 
under “Price and Payment,” for the car or cars, or the part of the 
delivery sampled, and this correction shall in no wise affect the mois¬ 
ture correction for other railroad cars or parts of the delivery that may 
be sampled, or the correction that shall apply for variations of ash and 
heating value as determined for the delivery or order. The special 
moisture sample shall be used for no other purpose than for determining 
moisture content, and the moisture content so determined shall be 
considered as final. 

13. When orders are issued for 50 tons or less, sampling shall be 
discretionary with the Government; and if samples are not taken, the 
bid price per ton shall be paid. 


PUBLICATIONS ON FUEL TECHNOLOGY. 


A limited supply of the following publications of the Bureau of 
Mines is temporarily available for free distribution. Requests for all 
publications can not be granted, and applicants should limit their 
selection to publications that may be of especial interest to them. 
Requests for publications should be addressed to the Director, Bureau 
of Mines, Washington, D. C. 

Bulletin 2 , North Dakota lignite as a fuel for power-plant boilers, by D. T. 
Randall and Henry Kreisinger. 1910, 42 pp., 1 pi., 7 figs. 

Bulletin 4. Features of producer-gas power-plant development in Europe, by 
R. H. Fernald. 1910. 27 pp., 4 pis., 7 figs. 

Bulletin 5. Washing and coking tests of coal at Denver, Colo., July 1, 1908, to 
June 30, 1909, by A. W. Belden, G. R. Delamater, J. J. Groves, and K. M. Way. 
1910. G2pp., Ifig. 

Bulletin 6 . Coals available for the manufacture of illuminating gas, by A. II. 
White and Perry Barker, compiled and revised by H. M. Wilson. 1911. 77 pp., 
4 pis., 12 figs. 

Bulletin 13. Resume of producer-gas investigations, October 1, 1904, to June 30, 
1910, by R. H. Fernald and C. D. Smith. 1911. 393 pp., 12 pis., 250 figs. 

Bulletin 14. Briquetting tests of lignite at Pittsburgh, Pa., 1908-9; with a chapter 
on sulphite-pitch binder, by C. L. Wright. 1911. 64 pp., 11 pis., 4 figs. 

. Bulletin 16. The uses of peat for fuel and other purposes, by C. A. Davis. 1911. 
214 pp., 1 pi., 1 fig. 

Bulletin 18. The transmission of heat into steam boilers, by Henry Kreisinger 
and W. T. Ray. 1912. 180 pp., 78 figs. 

Bulletin 24. Binders for coal briquets, by J. E. Mills. 56 pp., 1 fig. Reprint 
of United States Geological Survey Bulletin 343. 

Bulletin 27. Tests of coal and briquets as fuel for house-heating boilers, by D. T. 
Randall. 44 pp., 3 pis., 2 figs. Reprint of Uqited States Geological Survey Bulle¬ 
tin 366. 

Bulletin 28. Experimental work conducted in the chemical laboratory of the 
United States fuel-testing plant at St. Louis, Mo., January 1, 1905, to July 31, 1906, 
by N. W. Lord. 51 pp. Reprint of United States Geological Survey Bulletin 323. 

Bulletin 31. Incidental problems in gas-producer tests, by R. H. Fernald, C. D. 
Smith, J. K. Clement, and H. A. Grine. 29 pp., 8 figs. Reprint of United States 
Geological Survey Bulletin 393. 

Bulletin 32. Commercial deductions from comparisons of gasoline and alcohol 
tests of internal-combustion engines, by R. M. Strong. 38 pp. Reprint of United 
States Geological Survey Bulletin 392. 

Bulletin 33. Comparative tests of run-of-mine and briquetted coal on the toi-pedo 
])oat BiddU, by W. T. Ray and Henry Kreisinger. 50 pp., 10 figs. Reprint of 
United States Geological Survey Bulletin 403. 

Bulletin 34. Tests of run-of-mine and briquetted coal in a locomotive boiler, by 
W. T. Ray and Henry Kreisinger. 33 pp., 9 figs. Reprint of United States Geo¬ 
logical Survey Bulletin 412. 

Bulletin 35. The utilization of fuel in locomcrtive practice, by W. F. M. Goss. 
29 pp., 8 figs. Reprint of United States Geological Survey Bulletin 402. 


59 


60 METHODS OF SAMPLING DELIVERED COAL. 

Bulletin 30. Alaskan coal problems, by W. L. Fisher, 1911. 32 pp., 1 pi. 

Bulletin 39. The smoke problem at boiler plants, a preliminary report, by B. T. 
Randall. 31 pp. Reprint of United States Geological Survey Bulletin 334, revised 
by S. B. Flagg. 

Bulletin 40. The smokeless combustion of coal in boiler furnaces, with a chapter 
on central heating plants, by D. T. Randall and H. W. Weeks. 188 pp., 40 figs. 
Reprint of United States Geological Survey Bulletin 373, revised by Henry Kreisinger. 

Bulletin 49. City smoke ordinances and smoke abatement, by S. B. Flagg. 1912. 
55 pp. 

Bulletin 54. Foundry cupola gases and temperatures, by A. W. Belden. 1913. 
29 pp., 3 pis., 16 figs. 

Bulletin 55. The commercial trend of the producer-gas power plant in the United 
States, by R. H. Fernald. 1913. 93 pp., 1 pi., 4 figs. 

Bulletin 56. First series of coal-dust tests in the experimental mine, by G. S. 
Rice, L. M. Jones, J. K. Clement, and W. L. Egy. 1913. 115 pp., 12 pis., 28 figs. 

Bulletin 58. Fuel-briquetting investigations, July, 1904, to July, 1912, by C. Ij. 
Wright. 1913. 277 pp., 21 pis., 3 figs. 

Bulletin 76. United States coals available for export trade, by Van. H. Manning. 
1914. 15pp.,lpl. 

Bulletin 97. Sampling and analyzing fine gases, by Henry Kreisinger and F. K. 
Ovitz. 1915. 70 pp., 1 pi., 36 figs. 

Technical Paper 2 . The escape of gas from coal, by H. C. Porter and H. C. Ovitz. 
1911. 14pp.,lfig. 

Technical Paper 3. Specifications for the purchase of fuel oil for the Government, 
with directions for sampling oil and natural gas, by I. C. Allen. 1911. 13 pp. 

Technical Paper 5. The constituents of coal soluble in phenol, by J. C. W. Frazer 
and E. J. Hoffman. 1912. 20 pp., 1 pi. 

Technical Paper 8 . Methods of analyzing coal and coke, by F. M. Stanton and 
A. C. Fieldner. 1913. 42 pp., 12 figs. 

Technical Paper 10. Liquefied products of natural gas; their properties and uses, 
by I. C. Allen and G. A. Burrell. 1912. 23 pp. 

Technical Paper 16. Deterioration and spontaneous combustion of coal in 
storage, a preliminary report, by H. C. Porter and F. K. Ovitz. 1912. 14 pp. 

Technical Paper 25. Methods for the determination of water in petroleum and 
its products, by I. C. Allen and W. A. Jacobs. 1912. 13 pp., 2 figs. 

Technical Paper 34. Experiments with furnaces for a hand-fired return tubular 
boiler, by S. B. Flagg, G. C. Cook, and F. E. Woodman. 1914. 32 pp., 1 pL, 4 figs. 

Technical Paper 35. Weathering of the Pittsburgh coal bed at the experimental 
mine near Bruceton, Pa., by H. C. Porter and A. C.‘Fieldner, 1914. 35 pp., 14 figs. 

Technical Paper 37. Heavy oil as fuel for internal combustion engines, by I. C. 
Allen. 1913. 36 pp. 

Technical Paper 38. Wastes in the production and utilization of natural gas, 
and methods for their prevention, by Ralph Arnold and F. G. Clapp. 1913. 29 pp. 

Technical Paper 45. Waste of oil and gas in the IVlid-Continent fields, by R. S. 
Blatchley. 1914. 54 pp., 2 pis., 15 figs. 

Technical Paper 49. The flash point of oils, methods, and apparatus for its de¬ 
termination, by I. C. Allen and A. S. Crossfield. 1913. 31 pp., 2 figs. 

Technical Paper 50. Metallurgical coke, by A. W. Belden. 1913. 48 pp,, 1 pL, 
23 figs. 

Technical Paper 55. The production and use of brown coal in the vicinity of 
Cologne, Germany, by C. A. Davis. 1913. 15 pp. 

Technical Paper 57. A preliminary report on the utilization of petroleum and 
natural gas in Wyoming, by W. R. Calvert, wdth a discussion of the suitability of 
natural gas for making gasoline, by G. A. Burrell. 1913. 23 pp. 


PUBLICATIONS ON FUEL TECHNOLOGY. 


G1 


Technical Paper G3. Factors governing the combustion of coal in boiler furnaces; 
a preliminary report, by J. K. Clement, J. C. W. Frazer, and C. E. Augustine. 1914. 
46 pp., 26 figs. 

Technical Paper 65. A study of the oxidation of coal, by H. C. Porter. 1914. 
30 pp., 12 figs. 

Technical Paper 74. Physical and chemical properties of the petroleums of Cali¬ 
fornia, by I. C. Allen, W. A. Jacobs, A. S. Crossfield, and R. R. Mathews. • 1914. 
38 pp., 1 fig. 

Technical Paper 76. Notes on the sampling and analysis of coal, by A. C. Fieldner. 

1914. 59 pp., 6 figs. 

Technical Paper 97. Saving fuel in heating a house, by L. P. Breckenridge, and 
S. B. Flagg. 1915. 35 pp., 3 figs. 

Technical Paper 104. Analysis of natural gas and illuminating gas by fractional 
distillation at low temperatures and pressures, by G. A. Burrell, F. M. Seibert, and 
I. W. Robertson. 1915. 41 pp., 7 figs. 

Technical Paper 109. Composition of the natural gas used in twenty-five cities, 
with a discussion of the properties of natural gas, by G. A. Burrell and G. G. Oberfell. 

1915. 22 pp. 

Technical Paper 113. Some properties of the water in coal, by H. C. Porter and 
O. C. Ralston. 1916. 30 pp. 

Technical Paper 114. Heat transmission through boiler tubes, by Henry Kreisin- 
ger and J. F. Barkley. 1915. 36 pp., 23 figs. 

Technical Paper 115. Inflammability of mixtures of gasoline vapor and air, by 
G. A. Burrell and H. T. Boyd. 1915. 18 pp., 2 figs. 

Technical Paper 123. Notes on the use of low-grade fuel in Europe, hy R. H. 
Fernald. 1915. 37 pp. 

Technical Paper 127. Hazards in handling gasoline, by G. A. Burrell. 1916. 



INDEX. 


Alternate-shovel sampling. 26,56,57 

Analyses of coal samples, reporting of.39,40 

requirements for. 48 

Anthracite coal, commercial sizes of. 45 


domestic sizes of, requirements regarding, 

43,52,53 


for power plants, requirements regarding. 48,49 

specifications for. 43,44 

See also Buckwheat coal; Pea coal. 

“As received” basis for specifications, ob¬ 
jections to. 6,7 

Ash in coal, effect of. 10 

proportion of, factors affecting. 10 

variations in.:. 43 

price adjustment for.42,51,53 

B. 

Bailey, E. G., on sampling coal. 13 

Bidders, information supplied by, form for.. 53,54 

Bids, methods of comparing. 49 

rejection of. 47,49 

requirements regarding. 47 

See also Proposals. 

Bituminous coal for power plants, require¬ 
ments regarding.48,49 

See also Coal. 

Bond of contractor, requirements regarding.. 46,47 

Brunton, D. W., on crushing of ore. 24 

on method of sampling ores. 27 

Buckwheat coal for power plants, require¬ 
ments regarding.48-51 

Bureau of Mines, investigations of. 19 

method of sampling by. 14,15 

sampling room of, description of. 32 

specifications prepared by. 6 

testing of coal by. 3 

C. 

Car samples of coal, collection of. 18 

impurities in. 4 

Cargo, shipments of coal, collection of sam¬ 
ples from. 15,18-20 

method of sampling. 15 

Clinkering, causes of. 12 

Coal, determination of price for. 51 

from stock piled, moisture in, determina¬ 
tion of. 8,9 

in cars, effect of rain on. 8 

paj'ment for, regulations regarding.51-53 

variations in, price corrections for. 42 

Coal-sampling plant, figure showing. 31 

operation of. 32 

view of. 32 

Collectors of coal samples, qualifications of.. 20 

Coning of gross sample, method for. 26,27,57 


Page. 

Containers, coal-sample, description of. 36 

filling of. 27,28,38 

form accompanying. 37,38,39 

sealing of. 38 

View showing. 32 

types of. 36 

Contract, award of, factors determining. 52 

requirements for.49,50 

cancellation of, causes for.50,53 

requirements regarding. 47 

Contractor, bond of.46,47 

Crushing coal samples, factors in.23,25 

ores, factors determining. 24 

D. 

Delivery of coal, requirements for. 48 


District of Columbia, collection of samples in. 30-35 


“Dry-coal” basis for specifications, merits of. 7 

G. 

Gross sample, collection of.16-18,55 

crushed, views of. 26 

method of crushing. 23 

mixing of. 23,26,56 

preparation of.23,56 

view of. 56 

quartered, view of. 26 

receptacles for.20,21 

reduction of.23,56 

size of. 5,56 

factors determinmg.13,14 

II. 

Hampton Roads, Va.,crusher installed at... 19 

Heating plants, coal for, requirements regard¬ 
ing.48,49 

Heating value of coal, factor determining.... 10 

specifications for. 43 

variations in, price adjustment for.42,51 

I. 

Isthmus of Panama, sampling of coal shipped 

to.19,43 

L. 

Ladle for collecting samples. 19 

M. 

Mailing of coal samples.36-38 

Mechanical crusher, precautions in use of.... 29 

Mechanical sampling of coal, advantages of.. 16 

method for. 16 

Mine samples of coal, collection of. 4,5 

value of. 5 

Mixing and reducing machine, advantage of.. 28,29 

description of. 30 

view of. 28 


63 














































































64 


INDEX. 


Page. 


Moisture in coal, factors affecting. 6,7 

losses of. 6,7 

variations in. 6,7 

price adjustment for. 52 

N. 

Newport News, Va., sampling of coal at. 19 

Norfolk, Va., sampling of coal at. 19 

O. 

Ores, crushing of, factors determining. 24 

P. 

Panama, sampling of coal shipped to. 19,43 

Parallin for sealing containers, objections to.. 36 

Pea coal for power plants, requirements re¬ 
garding. 48-51 

Power plants, coal for, requirements regard¬ 
ing.48,49 

Proposals for coal, requirements regarding... 46 

See also Bids. 

Purchase of coal, specification method for, 

difficulties in. 4 

growth of. 3 

purpose of.40,41 

requirements for. 6 

value of. 3 

Purchased coal, classification of. 40 

regulations regarding. 47 

Q. 

Quartering coal sample, method of.27,57 

R. 

Reducing buckets, use of.28,29 

See also Sampling buckets. 

Reducing machine. See Mixing and reduc¬ 
ing machine. 

Rejected coal, removal of. 50 

Rejection of coal, causes for.50,53 

Richards, R. H., on reduction of ore samples. 28 

Riffle of sampling plant, construction of. 32 

figure showing. 33 

view of. 32 


Page. 

Samples of coal, mine, collection of. 4 

size of. 55 

time of collecting. 15 

See also Gross samples. 

Sampling buckets, description of.29,30 

view of. 28 

See also Reducing bucket. 

Sampling of coal, factors involved in. 5,6 

importance of. 41 

Sampling coal, method of. 4-6,25,26,34,35 

precautions in.12,13 

requirements regarding. 48 

time for. 55 

See also Coal samples. 

Sampling room, description of. 32 

Sealing wax for sealing containers, objections 

to. 36 

Shovel, sampling by means of. 16 

Solder, for sealing containers, objections to.. 36 
“ Special moisture samples,” collection of. 9,21,22,58 

preparation of.9,21,22 

protection of. 9 

Sulphur as cause of clinlier. 11,12 

in coal, penalties for. 12 

T. 

Treasury Department, purchase of coal by... 3 

U. 

U. S. Geological Survey, work of. 3- 


V. 

Vessels, coal unloaded from, collection of 


samples from. 20 

Volatile matter in coal, specifications regard¬ 
ing. 11 

variations in, penalties for. 1] 

W. 

Wagons, collect ion o f samples from. 17 


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